diff --git a/.changeset/theme-check-json-contract.md b/.changeset/theme-check-json-contract.md
new file mode 100644
index 00000000000..4782eab7bab
--- /dev/null
+++ b/.changeset/theme-check-json-contract.md
@@ -0,0 +1,5 @@
+---
+'@shopify/cli': major
+---
+
+Return `valid` and flat `issues` with camelCase zero-based positions from Theme Check JSON output, retaining every requested environment and failing blocking validations.
diff --git a/docs-shopify.dev/generated/generated_docs_data_v2.json b/docs-shopify.dev/generated/generated_docs_data_v2.json
index a7b0525449c..ed5662391ef 100644
--- a/docs-shopify.dev/generated/generated_docs_data_v2.json
+++ b/docs-shopify.dev/generated/generated_docs_data_v2.json
@@ -8427,6 +8427,15 @@
           "isOptional": true,
           "environmentValue": "SHOPIFY_FLAG_ENVIRONMENT"
         },
+        {
+          "filePath": "docs-shopify.dev/commands/interfaces/theme-check.interface.ts",
+          "syntaxKind": "PropertySignature",
+          "name": "-j, --json",
+          "value": "''",
+          "description": "Output the result as JSON. Automatically disables color output.",
+          "isOptional": true,
+          "environmentValue": "SHOPIFY_FLAG_JSON"
+        },
         {
           "filePath": "docs-shopify.dev/commands/interfaces/theme-check.interface.ts",
           "syntaxKind": "PropertySignature",
@@ -8446,7 +8455,7 @@
           "environmentValue": "SHOPIFY_FLAG_VERSION"
         }
       ],
-      "value": "export interface themecheck {\n  /**\n   * Alias of the Shopify account to use for authentication.\n   * @environment SHOPIFY_FLAG_AUTH_ALIAS\n   */\n  '--auth-alias <value>'?: string\n\n  /**\n   * Automatically fix offenses\n   * @environment SHOPIFY_FLAG_AUTO_CORRECT\n   */\n  '-a, --auto-correct'?: ''\n\n  /**\n   * Use the config provided, overriding .theme-check.yml if present\n      Supports all theme-check: config values, e.g., theme-check:theme-app-extension,\n      theme-check:recommended, theme-check:all\n      For backwards compatibility, :theme_app_extension is also supported \n   * @environment SHOPIFY_FLAG_CONFIG\n   */\n  '-C, --config <value>'?: string\n\n  /**\n   * The environment to apply to the current command.\n   * @environment SHOPIFY_FLAG_ENVIRONMENT\n   */\n  '-e, --environment <value>'?: string\n\n  /**\n   * Minimum severity for exit with error code\n   * @environment SHOPIFY_FLAG_FAIL_LEVEL\n   */\n  '--fail-level <value>'?: string\n\n  /**\n   * Generate a .theme-check.yml file\n   * @environment SHOPIFY_FLAG_INIT\n   */\n  '--init'?: ''\n\n  /**\n   * Print the command's JSON schemas.\n   * @environment SHOPIFY_FLAG_JSON_SCHEMA\n   */\n  '--json-schema'?: ''\n\n  /**\n   * List enabled checks\n   * @environment SHOPIFY_FLAG_LIST\n   */\n  '--list'?: ''\n\n  /**\n   * Disable color output.\n   * @environment SHOPIFY_FLAG_NO_COLOR\n   */\n  '--no-color'?: ''\n\n  /**\n   * Disable interactive prompts and browser authentication.\n   * @environment SHOPIFY_FLAG_NO_INPUT\n   */\n  '--no-input'?: ''\n\n  /**\n   * The output format to use\n   * @environment SHOPIFY_FLAG_OUTPUT\n   */\n  '-o, --output <value>'?: string\n\n  /**\n   * The path where you want to run the command. Defaults to the current working directory.\n   * @environment SHOPIFY_FLAG_PATH\n   */\n  '--path <value>'?: string\n\n  /**\n   * Output active config to STDOUT\n   * @environment SHOPIFY_FLAG_PRINT\n   */\n  '--print'?: ''\n\n  /**\n   * Increase the verbosity of the output. May include sensitive data.\n   * @environment SHOPIFY_FLAG_VERBOSE\n   */\n  '--verbose'?: ''\n\n  /**\n   * Print Theme Check version\n   * @environment SHOPIFY_FLAG_VERSION\n   */\n  '-v, --version'?: ''\n}"
+      "value": "export interface themecheck {\n  /**\n   * Alias of the Shopify account to use for authentication.\n   * @environment SHOPIFY_FLAG_AUTH_ALIAS\n   */\n  '--auth-alias <value>'?: string\n\n  /**\n   * Automatically fix offenses\n   * @environment SHOPIFY_FLAG_AUTO_CORRECT\n   */\n  '-a, --auto-correct'?: ''\n\n  /**\n   * Use the config provided, overriding .theme-check.yml if present\n      Supports all theme-check: config values, e.g., theme-check:theme-app-extension,\n      theme-check:recommended, theme-check:all\n      For backwards compatibility, :theme_app_extension is also supported \n   * @environment SHOPIFY_FLAG_CONFIG\n   */\n  '-C, --config <value>'?: string\n\n  /**\n   * The environment to apply to the current command.\n   * @environment SHOPIFY_FLAG_ENVIRONMENT\n   */\n  '-e, --environment <value>'?: string\n\n  /**\n   * Minimum severity for exit with error code\n   * @environment SHOPIFY_FLAG_FAIL_LEVEL\n   */\n  '--fail-level <value>'?: string\n\n  /**\n   * Generate a .theme-check.yml file\n   * @environment SHOPIFY_FLAG_INIT\n   */\n  '--init'?: ''\n\n  /**\n   * Output the result as JSON. Automatically disables color output.\n   * @environment SHOPIFY_FLAG_JSON\n   */\n  '-j, --json'?: ''\n\n  /**\n   * Print the command's JSON schemas.\n   * @environment SHOPIFY_FLAG_JSON_SCHEMA\n   */\n  '--json-schema'?: ''\n\n  /**\n   * List enabled checks\n   * @environment SHOPIFY_FLAG_LIST\n   */\n  '--list'?: ''\n\n  /**\n   * Disable color output.\n   * @environment SHOPIFY_FLAG_NO_COLOR\n   */\n  '--no-color'?: ''\n\n  /**\n   * Disable interactive prompts and browser authentication.\n   * @environment SHOPIFY_FLAG_NO_INPUT\n   */\n  '--no-input'?: ''\n\n  /**\n   * The output format to use\n   * @environment SHOPIFY_FLAG_OUTPUT\n   */\n  '-o, --output <value>'?: string\n\n  /**\n   * The path where you want to run the command. Defaults to the current working directory.\n   * @environment SHOPIFY_FLAG_PATH\n   */\n  '--path <value>'?: string\n\n  /**\n   * Output active config to STDOUT\n   * @environment SHOPIFY_FLAG_PRINT\n   */\n  '--print'?: ''\n\n  /**\n   * Increase the verbosity of the output. May include sensitive data.\n   * @environment SHOPIFY_FLAG_VERBOSE\n   */\n  '--verbose'?: ''\n\n  /**\n   * Print Theme Check version\n   * @environment SHOPIFY_FLAG_VERSION\n   */\n  '-v, --version'?: ''\n}"
     }
   },
   "themeconsole": {
diff --git a/packages/cli-kit/src/public/node/base-command.ts b/packages/cli-kit/src/public/node/base-command.ts
index 8a23e55beb2..8f05c1fbeb6 100644
--- a/packages/cli-kit/src/public/node/base-command.ts
+++ b/packages/cli-kit/src/public/node/base-command.ts
@@ -1,7 +1,13 @@
 import {isDevelopment} from './context/local.js'
 import {addPublicMetadata} from './metadata.js'
 import {AbortError} from './error.js'
-import {commandEventOutputMode, emitCommandEvent, runWithCommandEventsForCommand} from './command-events.js'
+import {
+  commandEventOutputMode,
+  emitCommandEvent,
+  renderCommandEventAsJson,
+  runWithCommandEvents,
+  runWithCommandEventsForCommand,
+} from './command-events.js'
 import {outputContent, outputResult, outputToken} from './output.js'
 import {setCurrentSessionAlias} from './session.js'
 import {terminalSupportsPrompting} from './system.js'
@@ -73,11 +79,19 @@ abstract class BaseCommand extends Command {
     return undefined
   }
 
+  private jsonOutputFromEnvironment = false
+
   async catch(error: Error & {skipOclifErrorHandling: boolean}): Promise<void> {
-    error.skipOclifErrorHandling = true
-    const {errorHandler} = await import('./error-handler.js')
-    await errorHandler(error, this.config)
-    return Errors.handle(error)
+    const handleError = async () => {
+      error.skipOclifErrorHandling = true
+      const {errorHandler} = await import('./error-handler.js')
+      await errorHandler(error, this.config)
+      return Errors.handle(error)
+    }
+    if (this.jsonOutputFromEnvironment && commandEventOutputMode() !== 'json') {
+      return runWithCommandEvents({outputMode: 'json', sink: renderCommandEventAsJson}, handleError)
+    }
+    return handleError()
   }
 
   protected async _run<T>(): Promise<T> {
@@ -250,6 +264,12 @@ ${explanation} in non-interactive terminal environments, such as a CI environmen
     // command-line arguments.
     const noDefaultsResult = await super.parse<TFlags, TGlobalFlags, TArgs>(noDefaultsOptions(options), argv)
 
+    // Remember the requested format before environment flag validation can fail.
+    const effectiveFlags = {...environment, ...noDefaultsResult.flags}
+    this.jsonOutputFromEnvironment =
+      (commandSupportsFlag(options?.flags, 'json') && effectiveFlags.json === true) ||
+      (commandSupportsFlag(options?.flags, 'output') && effectiveFlags.output === 'json')
+
     // Add the environment's settings to argv and pass them to `super.parse`. This
     // invokes oclif's validation system without breaking the oclif black box.
     // Replace the original result with this one.
@@ -261,12 +281,18 @@ ${explanation} in non-interactive terminal environments, such as a CI environmen
     ])
 
     // Report successful application of the environment.
-    reportEnvironmentApplication<TFlags, TGlobalFlags, TArgs>(
-      noDefaultsResult.flags,
-      result.flags,
-      isDefaultEnvironment ? 'default' : (environments[0] as string),
-      environment,
-    )
+    const report = () =>
+      reportEnvironmentApplication<TFlags, TGlobalFlags, TArgs>(
+        noDefaultsResult.flags,
+        result.flags,
+        isDefaultEnvironment ? 'default' : (environments[0] as string),
+        environment,
+      )
+    if ((result.flags.json || result.flags.output === 'json') && commandEventOutputMode() !== 'json') {
+      runWithCommandEvents({outputMode: 'json', sink: renderCommandEventAsJson}, report)
+    } else {
+      report()
+    }
 
     return result
   }
diff --git a/packages/cli-kit/src/public/node/error/index.test.ts b/packages/cli-kit/src/public/node/error/index.test.ts
index 9958fe57271..142ceba9bf3 100644
--- a/packages/cli-kit/src/public/node/error/index.test.ts
+++ b/packages/cli-kit/src/public/node/error/index.test.ts
@@ -9,6 +9,7 @@ import {
 import {jsonOutputEnabled} from '../environment.js'
 import {renderFatalError} from '../ui.js'
 import {mockAndCaptureOutput} from '../testing/output.js'
+import {runWithCommandEvents} from '../command-events.js'
 import {ClientError} from 'graphql-request'
 import {beforeEach, describe, expect, test, vi} from 'vitest'
 
@@ -90,6 +91,15 @@ describe('handler', () => {
     expect(renderFatalError).not.toHaveBeenCalled()
   })
 
+  test('renders JSON when the command selects JSON output without a global flag', async () => {
+    const output = mockAndCaptureOutput()
+
+    await runWithCommandEvents({outputMode: 'json', sink: () => {}}, () => handler(new AbortError('Expected failure')))
+
+    expect(JSON.parse(output.info())).toStrictEqual({error: {type: 'abort', message: 'Expected failure'}})
+    expect(renderFatalError).not.toHaveBeenCalled()
+  })
+
   test('keeps JSON silent aborts silent', async () => {
     vi.mocked(jsonOutputEnabled).mockReturnValue(true)
 
diff --git a/packages/cli-kit/src/public/node/error/index.ts b/packages/cli-kit/src/public/node/error/index.ts
index 2b608baddb7..b136f1ba440 100644
--- a/packages/cli-kit/src/public/node/error/index.ts
+++ b/packages/cli-kit/src/public/node/error/index.ts
@@ -150,7 +150,8 @@ export async function handler(error: unknown): Promise<unknown> {
   }
 
   const {jsonOutputEnabled} = await import('../environment.js')
-  if (jsonOutputEnabled()) {
+  const {commandEventOutputMode} = await import('../../../private/node/command-event-context.js')
+  if (jsonOutputEnabled() || commandEventOutputMode() === 'json') {
     const {renderFatalErrorAsJson} = await import('../../../private/node/json-error.js')
     renderFatalErrorAsJson(fatal)
     await flushStdout()
diff --git a/packages/cli/README.md b/packages/cli/README.md
index 3b91155b56f..7992da27634 100644
--- a/packages/cli/README.md
+++ b/packages/cli/README.md
@@ -11563,8 +11563,8 @@ Validate the theme.
 ```
 USAGE
   $ shopify theme check [--auth-alias <value>] [-a] [-C <value>] [-e <value>...] [--fail-level
-    crash|error|suggestion|style|warning|info] [--init] [--json-schema] [--list] [--no-color] [--no-input] [-o
-    text|json] [--path <value>] [--print] [--verbose] [-v]
+    crash|error|suggestion|style|warning|info] [-j | --init | -v | --print | --list] [--json-schema] [--no-color]
+    [--no-input] [-o text|json] [--path <value>] [--verbose]
 
 FLAGS
   -C, --config=<value>
@@ -11582,6 +11582,10 @@ FLAGS
       The environment to apply to the current command.
       [env: SHOPIFY_FLAG_ENVIRONMENT]
 
+  -j, --json
+      Output the result as JSON. Automatically disables color output.
+      [env: SHOPIFY_FLAG_JSON]
+
   -o, --output=<option>
       [default: text] The output format to use
       [env: SHOPIFY_FLAG_OUTPUT]
@@ -11638,6 +11642,322 @@ DESCRIPTION
   Calls and runs "Theme Check" (https://shopify.dev/docs/themes/tools/theme-check) to analyze your theme code for errors
   and to ensure that it follows theme and Liquid best practices. "Learn more about the checks that Theme Check runs."
   (https://shopify.dev/docs/themes/tools/theme-check/checks)
+
+  Use `--json-schema` to print the result, error, and event schemas.
+
+  Output from `--json` conforms to the `ThemeCheckResult` schema.
+
+  ```json
+  {
+    "anyOf": [
+      {
+        "$ref": "#/definitions/ThemeEnvironment/anyOf/0/properties/result"
+      },
+      {
+        "type": "object",
+        "properties": {
+          "environments": {
+            "type": "array",
+            "items": {
+              "$ref": "#/definitions/ThemeEnvironment"
+            }
+          }
+        },
+        "required": [
+          "environments"
+        ],
+        "additionalProperties": false
+      }
+    ],
+    "title": "ThemeCheckResult",
+    "definitions": {
+      "ThemeCheckIssue": {
+        "type": "object",
+        "properties": {
+          "filePath": {
+            "type": "string",
+            "description": "The absolute native path of the file."
+          },
+          "check": {
+            "type": "string"
+          },
+          "severity": {
+            "type": "string",
+            "enum": [
+              "error",
+              "warning",
+              "info"
+            ]
+          },
+          "startRow": {
+            "type": "integer",
+            "minimum": 0,
+            "description": "The zero-based starting line."
+          },
+          "startColumn": {
+            "type": "integer",
+            "minimum": 0,
+            "description": "The zero-based starting column."
+          },
+          "endRow": {
+            "type": "integer",
+            "minimum": 0,
+            "description": "The zero-based ending line."
+          },
+          "endColumn": {
+            "type": "integer",
+            "minimum": 0,
+            "description": "The zero-based ending column."
+          },
+          "message": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "filePath",
+          "check",
+          "severity",
+          "startRow",
+          "startColumn",
+          "endRow",
+          "endColumn",
+          "message"
+        ],
+        "additionalProperties": false
+      },
+      "ThemeEnvironment": {
+        "anyOf": [
+          {
+            "type": "object",
+            "properties": {
+              "environment": {
+                "type": "string"
+              },
+              "result": {
+                "anyOf": [
+                  {
+                    "type": "object",
+                    "properties": {
+                      "valid": {
+                        "type": "boolean",
+                        "description": "Whether the validation passes the selected blocking policy."
+                      },
+                      "issues": {
+                        "type": "array",
+                        "items": {
+                          "$ref": "#/definitions/ThemeCheckIssue"
+                        }
+                      },
+                      "errorCount": {
+                        "type": "integer",
+                        "minimum": 0
+                      },
+                      "warningCount": {
+                        "type": "integer",
+                        "minimum": 0
+                      },
+                      "infoCount": {
+                        "type": "integer",
+                        "minimum": 0
+                      }
+                    },
+                    "required": [
+                      "valid",
+                      "issues",
+                      "errorCount",
+                      "warningCount",
+                      "infoCount"
+                    ],
+                    "additionalProperties": false
+                  },
+                  {
+                    "type": "object",
+                    "properties": {
+                      "status": {
+                        "type": "string",
+                        "const": "cancelled"
+                      }
+                    },
+                    "required": [
+                      "status"
+                    ],
+                    "additionalProperties": false
+                  }
+                ]
+              }
+            },
+            "required": [
+              "environment",
+              "result"
+            ],
+            "additionalProperties": false
+          },
+          {
+            "type": "object",
+            "properties": {
+              "environment": {
+                "type": "string"
+              },
+              "error": {
+                "anyOf": [
+                  {
+                    "type": "object",
+                    "properties": {
+                      "type": {
+                        "type": "string",
+                        "const": "abort"
+                      },
+                      "message": {
+                        "type": "string"
+                      },
+                      "code": {
+                        "type": "string",
+                        "minLength": 1,
+                        "description": "A stable error code, included only when known."
+                      },
+                      "tryMessage": {
+                        "type": "string"
+                      },
+                      "nextSteps": {
+                        "type": "array",
+                        "items": {
+                          "type": "string"
+                        }
+                      },
+                      "customSections": {
+                        "type": "array",
+                        "items": {
+                          "type": "object",
+                          "properties": {
+                            "title": {
+                              "type": "string"
+                            },
+                            "body": {
+                              "anyOf": [
+                                {
+                                  "type": "string"
+                                },
+                                {
+                                  "type": "array",
+                                  "items": {
+                                    "type": "array",
+                                    "items": {
+                                      "type": "string"
+                                    }
+                                  }
+                                }
+                              ]
+                            }
+                          },
+                          "required": [
+                            "body"
+                          ],
+                          "additionalProperties": false
+                        }
+                      },
+                      "details": {
+                        "description": "Selected domain details, preserving native API payloads such as GraphQL errors, extensions, and data."
+                      }
+                    },
+                    "required": [
+                      "type",
+                      "message"
+                    ],
+                    "additionalProperties": false
+                  },
+                  {
+                    "type": "object",
+                    "properties": {
+                      "type": {
+                        "type": "string",
+                        "const": "bug"
+                      },
+                      "message": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/message"
+                      },
+                      "code": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/code"
+                      },
+                      "tryMessage": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/tryMessage"
+                      },
+                      "nextSteps": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/nextSteps"
+                      },
+                      "customSections": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/customSections"
+                      },
+                      "details": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/details"
+                      },
+                      "stack": {
+                        "type": "string"
+                      }
+                    },
+                    "required": [
+                      "type",
+                      "message"
+                    ],
+                    "additionalProperties": false
+                  },
+                  {
+                    "type": "object",
+                    "properties": {
+                      "type": {
+                        "type": "string",
+                        "const": "external"
+                      },
+                      "message": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/message"
+                      },
+                      "code": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/code"
+                      },
+                      "tryMessage": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/tryMessage"
+                      },
+                      "nextSteps": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/nextSteps"
+                      },
+                      "customSections": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/customSections"
+                      },
+                      "details": {
+                        "$ref": "#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/details"
+                      },
+                      "command": {
+                        "type": "string"
+                      },
+                      "args": {
+                        "type": "array",
+                        "items": {
+                          "type": "string"
+                        }
+                      }
+                    },
+                    "required": [
+                      "type",
+                      "message",
+                      "command",
+                      "args"
+                    ],
+                    "additionalProperties": false
+                  }
+                ]
+              }
+            },
+            "required": [
+              "environment",
+              "error"
+            ],
+            "additionalProperties": false
+          }
+        ]
+      }
+    },
+    "$schema": "http://json-schema.org/draft-07/schema#"
+  }
+  ```
 ```
 
 ## `shopify theme console`
diff --git a/packages/cli/oclif.manifest.json b/packages/cli/oclif.manifest.json
index 90910f7fddf..81f65535925 100644
--- a/packages/cli/oclif.manifest.json
+++ b/packages/cli/oclif.manifest.json
@@ -10518,7 +10518,7 @@
       "args": {
       },
       "customPluginName": "@shopify/theme",
-      "description": "Calls and runs \"Theme Check\" (https://shopify.dev/docs/themes/tools/theme-check) to analyze your theme code for errors and to ensure that it follows theme and Liquid best practices. \"Learn more about the checks that Theme Check runs.\" (https://shopify.dev/docs/themes/tools/theme-check/checks)",
+      "description": "Calls and runs \"Theme Check\" (https://shopify.dev/docs/themes/tools/theme-check) to analyze your theme code for errors and to ensure that it follows theme and Liquid best practices. \"Learn more about the checks that Theme Check runs.\" (https://shopify.dev/docs/themes/tools/theme-check/checks)\n\nUse `--json-schema` to print the result, error, and event schemas.\n\nOutput from `--json` conforms to the `ThemeCheckResult` schema.\n\n```json\n{\n  \"anyOf\": [\n    {\n      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/0/properties/result\"\n    },\n    {\n      \"type\": \"object\",\n      \"properties\": {\n        \"environments\": {\n          \"type\": \"array\",\n          \"items\": {\n            \"$ref\": \"#/definitions/ThemeEnvironment\"\n          }\n        }\n      },\n      \"required\": [\n        \"environments\"\n      ],\n      \"additionalProperties\": false\n    }\n  ],\n  \"title\": \"ThemeCheckResult\",\n  \"definitions\": {\n    \"ThemeCheckIssue\": {\n      \"type\": \"object\",\n      \"properties\": {\n        \"filePath\": {\n          \"type\": \"string\",\n          \"description\": \"The absolute native path of the file.\"\n        },\n        \"check\": {\n          \"type\": \"string\"\n        },\n        \"severity\": {\n          \"type\": \"string\",\n          \"enum\": [\n            \"error\",\n            \"warning\",\n            \"info\"\n          ]\n        },\n        \"startRow\": {\n          \"type\": \"integer\",\n          \"minimum\": 0,\n          \"description\": \"The zero-based starting line.\"\n        },\n        \"startColumn\": {\n          \"type\": \"integer\",\n          \"minimum\": 0,\n          \"description\": \"The zero-based starting column.\"\n        },\n        \"endRow\": {\n          \"type\": \"integer\",\n          \"minimum\": 0,\n          \"description\": \"The zero-based ending line.\"\n        },\n        \"endColumn\": {\n          \"type\": \"integer\",\n          \"minimum\": 0,\n          \"description\": \"The zero-based ending column.\"\n        },\n        \"message\": {\n          \"type\": \"string\"\n        }\n      },\n      \"required\": [\n        \"filePath\",\n        \"check\",\n        \"severity\",\n        \"startRow\",\n        \"startColumn\",\n        \"endRow\",\n        \"endColumn\",\n        \"message\"\n      ],\n      \"additionalProperties\": false\n    },\n    \"ThemeEnvironment\": {\n      \"anyOf\": [\n        {\n          \"type\": \"object\",\n          \"properties\": {\n            \"environment\": {\n              \"type\": \"string\"\n            },\n            \"result\": {\n              \"anyOf\": [\n                {\n                  \"type\": \"object\",\n                  \"properties\": {\n                    \"valid\": {\n                      \"type\": \"boolean\",\n                      \"description\": \"Whether the validation passes the selected blocking policy.\"\n                    },\n                    \"issues\": {\n                      \"type\": \"array\",\n                      \"items\": {\n                        \"$ref\": \"#/definitions/ThemeCheckIssue\"\n                      }\n                    },\n                    \"errorCount\": {\n                      \"type\": \"integer\",\n                      \"minimum\": 0\n                    },\n                    \"warningCount\": {\n                      \"type\": \"integer\",\n                      \"minimum\": 0\n                    },\n                    \"infoCount\": {\n                      \"type\": \"integer\",\n                      \"minimum\": 0\n                    }\n                  },\n                  \"required\": [\n                    \"valid\",\n                    \"issues\",\n                    \"errorCount\",\n                    \"warningCount\",\n                    \"infoCount\"\n                  ],\n                  \"additionalProperties\": false\n                },\n                {\n                  \"type\": \"object\",\n                  \"properties\": {\n                    \"status\": {\n                      \"type\": \"string\",\n                      \"const\": \"cancelled\"\n                    }\n                  },\n                  \"required\": [\n                    \"status\"\n                  ],\n                  \"additionalProperties\": false\n                }\n              ]\n            }\n          },\n          \"required\": [\n            \"environment\",\n            \"result\"\n          ],\n          \"additionalProperties\": false\n        },\n        {\n          \"type\": \"object\",\n          \"properties\": {\n            \"environment\": {\n              \"type\": \"string\"\n            },\n            \"error\": {\n              \"anyOf\": [\n                {\n                  \"type\": \"object\",\n                  \"properties\": {\n                    \"type\": {\n                      \"type\": \"string\",\n                      \"const\": \"abort\"\n                    },\n                    \"message\": {\n                      \"type\": \"string\"\n                    },\n                    \"code\": {\n                      \"type\": \"string\",\n                      \"minLength\": 1,\n                      \"description\": \"A stable error code, included only when known.\"\n                    },\n                    \"tryMessage\": {\n                      \"type\": \"string\"\n                    },\n                    \"nextSteps\": {\n                      \"type\": \"array\",\n                      \"items\": {\n                        \"type\": \"string\"\n                      }\n                    },\n                    \"customSections\": {\n                      \"type\": \"array\",\n                      \"items\": {\n                        \"type\": \"object\",\n                        \"properties\": {\n                          \"title\": {\n                            \"type\": \"string\"\n                          },\n                          \"body\": {\n                            \"anyOf\": [\n                              {\n                                \"type\": \"string\"\n                              },\n                              {\n                                \"type\": \"array\",\n                                \"items\": {\n                                  \"type\": \"array\",\n                                  \"items\": {\n                                    \"type\": \"string\"\n                                  }\n                                }\n                              }\n                            ]\n                          }\n                        },\n                        \"required\": [\n                          \"body\"\n                        ],\n                        \"additionalProperties\": false\n                      }\n                    },\n                    \"details\": {\n                      \"description\": \"Selected domain details, preserving native API payloads such as GraphQL errors, extensions, and data.\"\n                    }\n                  },\n                  \"required\": [\n                    \"type\",\n                    \"message\"\n                  ],\n                  \"additionalProperties\": false\n                },\n                {\n                  \"type\": \"object\",\n                  \"properties\": {\n                    \"type\": {\n                      \"type\": \"string\",\n                      \"const\": \"bug\"\n                    },\n                    \"message\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/message\"\n                    },\n                    \"code\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/code\"\n                    },\n                    \"tryMessage\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/tryMessage\"\n                    },\n                    \"nextSteps\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/nextSteps\"\n                    },\n                    \"customSections\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/customSections\"\n                    },\n                    \"details\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/details\"\n                    },\n                    \"stack\": {\n                      \"type\": \"string\"\n                    }\n                  },\n                  \"required\": [\n                    \"type\",\n                    \"message\"\n                  ],\n                  \"additionalProperties\": false\n                },\n                {\n                  \"type\": \"object\",\n                  \"properties\": {\n                    \"type\": {\n                      \"type\": \"string\",\n                      \"const\": \"external\"\n                    },\n                    \"message\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/message\"\n                    },\n                    \"code\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/code\"\n                    },\n                    \"tryMessage\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/tryMessage\"\n                    },\n                    \"nextSteps\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/nextSteps\"\n                    },\n                    \"customSections\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/customSections\"\n                    },\n                    \"details\": {\n                      \"$ref\": \"#/definitions/ThemeEnvironment/anyOf/1/properties/error/anyOf/0/properties/details\"\n                    },\n                    \"command\": {\n                      \"type\": \"string\"\n                    },\n                    \"args\": {\n                      \"type\": \"array\",\n                      \"items\": {\n                        \"type\": \"string\"\n                      }\n                    }\n                  },\n                  \"required\": [\n                    \"type\",\n                    \"message\",\n                    \"command\",\n                    \"args\"\n                  ],\n                  \"additionalProperties\": false\n                }\n              ]\n            }\n          },\n          \"required\": [\n            \"environment\",\n            \"error\"\n          ],\n          \"additionalProperties\": false\n        }\n      ]\n    }\n  },\n  \"$schema\": \"http://json-schema.org/draft-07/schema#\"\n}\n```",
       "descriptionWithMarkdown": "Calls and runs [Theme Check](https://shopify.dev/docs/themes/tools/theme-check) to analyze your theme code for errors and to ensure that it follows theme and Liquid best practices. [Learn more about the checks that Theme Check runs.](https://shopify.dev/docs/themes/tools/theme-check/checks)",
       "enableJsonFlag": false,
       "flags": {
@@ -10584,6 +10584,21 @@
           "required": false,
           "type": "boolean"
         },
+        "json": {
+          "allowNo": false,
+          "char": "j",
+          "description": "Output the result as JSON. Automatically disables color output.",
+          "env": "SHOPIFY_FLAG_JSON",
+          "exclusive": [
+            "init",
+            "version",
+            "print",
+            "list"
+          ],
+          "hidden": false,
+          "name": "json",
+          "type": "boolean"
+        },
         "json-schema": {
           "allowNo": false,
           "description": "Print the command's JSON schemas.",
diff --git a/packages/eslint-plugin-cli/rules/json-output-command-exceptions.js b/packages/eslint-plugin-cli/rules/json-output-command-exceptions.js
index 18490a102f5..2a018c7439f 100644
--- a/packages/eslint-plugin-cli/rules/json-output-command-exceptions.js
+++ b/packages/eslint-plugin-cli/rules/json-output-command-exceptions.js
@@ -15,7 +15,6 @@ const commandExceptions = [
   'packages/plugin-did-you-mean/src/commands/config/autocorrect/off.ts',
   'packages/plugin-did-you-mean/src/commands/config/autocorrect/on.ts',
   'packages/plugin-did-you-mean/src/commands/config/autocorrect/status.ts',
-  'packages/theme/src/cli/commands/theme/check.ts',
   'packages/theme/src/cli/commands/theme/init.ts',
   'packages/theme/src/cli/commands/theme/metafields/pull.ts',
   'packages/theme/src/cli/commands/theme/package.ts',
diff --git a/packages/store/src/cli/commands/store/create/dev.test.ts b/packages/store/src/cli/commands/store/create/dev.test.ts
index 3ab37c1729f..4880cb92137 100644
--- a/packages/store/src/cli/commands/store/create/dev.test.ts
+++ b/packages/store/src/cli/commands/store/create/dev.test.ts
@@ -279,13 +279,16 @@ describe('store create dev command', () => {
     mockExit.mockRestore()
   })
 
-  test('does not output JSON for non-AbortError even when --json is active', async () => {
+  test('outputs one standard bug error for unexpected failures when --json is active', async () => {
     vi.mocked(createDevStore).mockRejectedValueOnce(new Error('unexpected'))
 
     await expect(
       StoreCreateDev.run(['--name', 'my-test-store', '--plan', 'plus', '--organization-id', '12345', '--json']),
     ).rejects.toThrow()
-    expect(vi.mocked(outputResult)).not.toHaveBeenCalled()
+    expect(outputResult).toHaveBeenCalledOnce()
+    expect(JSON.parse(vi.mocked(outputResult).mock.calls[0]![0] as string)).toEqual({
+      error: {type: 'bug', message: 'unexpected', stack: expect.stringContaining('Error: unexpected')},
+    })
   })
 
   test('does not output JSON for AbortError when --json is not active', async () => {
diff --git a/packages/store/src/cli/commands/store/delete.test.ts b/packages/store/src/cli/commands/store/delete.test.ts
index 1cc99f4f6ce..9de6d6a7ccb 100644
--- a/packages/store/src/cli/commands/store/delete.test.ts
+++ b/packages/store/src/cli/commands/store/delete.test.ts
@@ -195,13 +195,16 @@ describe('store delete command', () => {
     mockExit.mockRestore()
   })
 
-  test('does not output JSON for non-AbortError even when --json is active', async () => {
+  test('outputs one standard bug error for unexpected failures when --json is active', async () => {
     vi.mocked(deleteDevStore).mockRejectedValueOnce(new Error('unexpected'))
 
     await expect(
       StoreDelete.run(['--store', 'my-store.myshopify.com', '--organization-id', '12345', '--json']),
     ).rejects.toThrow()
-    expect(vi.mocked(outputResult)).not.toHaveBeenCalled()
+    expect(outputResult).toHaveBeenCalledOnce()
+    expect(JSON.parse(vi.mocked(outputResult).mock.calls[0]![0] as string)).toEqual({
+      error: {type: 'bug', message: 'unexpected', stack: expect.stringContaining('Error: unexpected')},
+    })
   })
 
   test('does not output JSON for AbortError when --json is not active', async () => {
diff --git a/packages/theme/src/cli/commands/theme/check-json.test.ts b/packages/theme/src/cli/commands/theme/check-json.test.ts
new file mode 100644
index 00000000000..85c4cc9f2da
--- /dev/null
+++ b/packages/theme/src/cli/commands/theme/check-json.test.ts
@@ -0,0 +1,365 @@
+import Check from './check.js'
+import {checkTheme, formatOffensesJson, sortOffenses} from '../../services/check.js'
+import {themeCheckJsonOutputSchema} from '../../services/check/types.js'
+import {encodeThemeCheckResult} from '../../services/check/result.js'
+import {expect, test, vi} from 'vitest'
+import {withCapturedStandardStreams} from '@shopify/cli-kit/node/testing/output'
+import {themeCheckRun, Severity, SourceCodeType, path as pathUtils} from '@shopify/theme-check-node'
+import {inTemporaryDirectory, writeFile} from '@shopify/cli-kit/node/fs'
+import {runWithCommandEventsForCommand} from '@shopify/cli-kit/node/command-events'
+// Native JSON paths must preserve Windows separators instead of pathe normalization.
+// eslint-disable-next-line no-restricted-imports
+import {resolve as resolvePath} from 'node:path'
+
+vi.mock('@shopify/theme-check-node', async (importOriginal) => ({
+  ...(await importOriginal<typeof import('@shopify/theme-check-node')>()),
+  themeCheckRun: vi.fn(),
+}))
+vi.mock('@shopify/cli-kit/node/environments')
+
+const offense = {
+  type: SourceCodeType.LiquidHtml,
+  check: 'ExampleCheck',
+  severity: Severity.ERROR,
+  uri: 'file:///theme/templates/index.liquid',
+  start: {index: 0, line: 0, character: 0},
+  end: {index: 1, line: 0, character: 1},
+  message: 'Example offense',
+}
+const emptyResult = {valid: true, issues: [], errorCount: 0, warningCount: 0, infoCount: 0}
+const invalidResult = {
+  valid: false,
+  issues: [
+    {
+      filePath: resolvePath(pathUtils.fsPath(offense.uri)),
+      check: 'ExampleCheck',
+      severity: 'error',
+      startRow: 0,
+      startColumn: 0,
+      endRow: 0,
+      endColumn: 1,
+      message: 'Example offense',
+    },
+  ],
+  errorCount: 1,
+  warningCount: 0,
+  infoCount: 0,
+}
+
+async function configuration() {
+  const {Config} = await import('@oclif/core')
+  const config = new Config({root: __dirname})
+  await config.load()
+  return config
+}
+
+test('projects the service model to flat issues with strict zero-based positions and counts', async () => {
+  expect(Check.jsonOutputSchema).toBe(themeCheckJsonOutputSchema)
+  vi.mocked(themeCheckRun).mockResolvedValue({offenses: [offense], theme: [], config: {} as never})
+  const {result} = await checkTheme('/theme')
+  expect(result).toEqual(formatOffensesJson(sortOffenses([offense])))
+  expect(JSON.parse(encodeThemeCheckResult(result))).toEqual(invalidResult)
+  expect(JSON.parse(encodeThemeCheckResult([]))).toEqual(emptyResult)
+  expect(() => themeCheckJsonOutputSchema.validate({...invalidResult, errorCount: '1'})).toThrow()
+  expect(() => themeCheckJsonOutputSchema.validate({...invalidResult, extra: true})).toThrow()
+  expect(() =>
+    themeCheckJsonOutputSchema.validate({...invalidResult, issues: [{...invalidResult.issues[0], startRow: -1}]}),
+  ).toThrow()
+  expect(() =>
+    themeCheckJsonOutputSchema.validate({
+      ...invalidResult,
+      issues: [{...invalidResult.issues[0], filePath: 'index.liquid'}],
+    }),
+  ).toThrow()
+})
+
+test.each(['--json', '--output=json'])('writes one validation result and exits nonzero for %s', async (flag) => {
+  await inTemporaryDirectory(async (directory) => {
+    const config = await configuration()
+    vi.mocked(themeCheckRun).mockResolvedValue({offenses: [offense], theme: [], config: {} as never})
+    const exit = vi.spyOn(process, 'exit').mockImplementation(() => undefined as never)
+    const previousExitCode = process.exitCode
+    try {
+      await withCapturedStandardStreams(async ({stdout, stderr}) => {
+        await new Check([`--path=${directory}`, flag], config).run()
+        expect(JSON.parse(stdout())).toEqual(invalidResult)
+        expect(stderr()).toBe('')
+      })
+      expect(process.exitCode).toBe(1)
+      expect(exit).not.toHaveBeenCalled()
+    } finally {
+      process.exitCode = previousExitCode
+    }
+  })
+})
+
+test.each(['init', 'version', 'print', 'list'])('rejects --json with --%s before execution', async (mode) => {
+  await expect(new Check(['--json', `--${mode}`], await configuration()).run()).rejects.toThrow()
+  expect(themeCheckRun).not.toHaveBeenCalled()
+})
+
+test.each(['success', 'single environment', 'partial failure', 'total failure', 'blocking validation'])(
+  'returns every requested environment in one document on %s',
+  async (mode) => {
+    await inTemporaryDirectory(async (directory) => {
+      const config = await configuration()
+      vi.mocked(themeCheckRun).mockResolvedValue({offenses: [], theme: [], config: {} as never})
+      if (mode === 'partial failure') vi.mocked(themeCheckRun).mockRejectedValueOnce(new Error('Check failed'))
+      if (mode === 'total failure') {
+        vi.mocked(themeCheckRun).mockImplementation(async () => {
+          throw new Error('Check failed')
+        })
+      }
+      if (mode === 'blocking validation')
+        vi.mocked(themeCheckRun).mockResolvedValueOnce({offenses: [offense], theme: [], config: {} as never})
+      const {loadEnvironment} = await import('@shopify/cli-kit/node/environments')
+      vi.mocked(loadEnvironment).mockResolvedValue({path: directory})
+      const previousExitCode = process.exitCode
+      process.exitCode = 0
+      try {
+        await withCapturedStandardStreams(async ({stdout, stderr}) => {
+          const argv = [
+            '--environment=first',
+            ...(mode === 'single environment' ? [] : ['--environment=second']),
+            '--json',
+          ]
+          await runWithCommandEventsForCommand(argv, () => new Check(argv, config).run())
+          const first = mode.includes('failure')
+            ? {environment: 'first', error: expect.objectContaining({message: 'Check failed'})}
+            : {environment: 'first', result: mode === 'blocking validation' ? invalidResult : emptyResult}
+          const second =
+            mode === 'total failure'
+              ? {environment: 'second', error: expect.objectContaining({message: 'Check failed'})}
+              : {environment: 'second', result: emptyResult}
+          expect(JSON.parse(stdout())).toEqual({
+            environments: mode === 'single environment' ? [first] : [first, second],
+          })
+          expect(process.exitCode).toBe(mode.includes('failure') || mode === 'blocking validation' ? 1 : 0)
+          if (mode.includes('failure')) expect(stderr()).toContain('Check failed')
+        })
+      } finally {
+        // Each test restores the process state after its asynchronous command has completed.
+        // eslint-disable-next-line require-atomic-updates
+        process.exitCode = previousExitCode
+      }
+    })
+  },
+)
+
+test.each(
+  ['json = true', 'output = "json"'].flatMap((setting) =>
+    [false, true].flatMap((mixed) =>
+      ['success', 'validation failure', 'execution failure'].map((outcome) => ({setting, mixed, outcome})),
+    ),
+  ),
+)(
+  'collects JSON selected in environment configuration: $setting, mixed=$mixed, outcome=$outcome',
+  async ({setting, mixed, outcome}) => {
+    await inTemporaryDirectory(async (directory) => {
+      await writeFile(
+        resolvePath(directory, 'shopify.theme.toml'),
+        [
+          '[environments.first]',
+          outcome === 'validation failure' ? '' : `path = ${JSON.stringify(directory)}`,
+          mixed ? '' : setting,
+          '[environments.second]',
+          `path = ${JSON.stringify(directory)}`,
+          setting,
+        ].join('\n'),
+      )
+      const {loadEnvironment} = await import('@shopify/cli-kit/node/environments')
+      const actual = await vi.importActual<typeof import('@shopify/cli-kit/node/environments')>(
+        '@shopify/cli-kit/node/environments',
+      )
+      vi.mocked(loadEnvironment).mockImplementation((environment, filename, options) =>
+        actual.loadEnvironment(environment, filename, {...options, from: directory}),
+      )
+      vi.mocked(themeCheckRun).mockResolvedValue({offenses: [], theme: [], config: {} as never})
+      if (outcome === 'execution failure') vi.mocked(themeCheckRun).mockRejectedValueOnce(new Error('Check failed'))
+      const config = await configuration()
+      const previousExitCode = process.exitCode
+      process.exitCode = 0
+      try {
+        await withCapturedStandardStreams(async ({stdout, stderr}) => {
+          const argv = ['-e', 'first', '-e', 'second']
+          await runWithCommandEventsForCommand(argv, () => new Check(argv, config).run())
+
+          expect(JSON.parse(stdout())).toEqual({
+            environments: [
+              outcome === 'success'
+                ? {environment: 'first', result: emptyResult}
+                : {
+                    environment: 'first',
+                    error: expect.objectContaining({
+                      message: outcome === 'validation failure' ? 'Missing flags: path' : 'Check failed',
+                    }),
+                  },
+              {environment: 'second', result: emptyResult},
+            ],
+          })
+          if (outcome === 'success') {
+            expect(stderr()).toBe('')
+          } else {
+            expect(JSON.parse(stderr())).toMatchObject({
+              type: 'diagnostic',
+              level: outcome === 'validation failure' ? 'warning' : 'error',
+              code: outcome === 'validation failure' ? 'theme-environment-invalid' : 'theme-environment-failed',
+              message: expect.stringContaining('first'),
+            })
+          }
+        })
+        expect(process.exitCode).toBe(outcome === 'success' ? 0 : 1)
+        expect(themeCheckRun).toHaveBeenCalledTimes(outcome === 'validation failure' ? 1 : 2)
+      } finally {
+        process.exitCode = previousExitCode
+      }
+    })
+  },
+)
+
+test.each(
+  ['json = true', 'output = "json"'].flatMap((setting) => [false, true].map((failure) => ({setting, failure}))),
+)(
+  'uses JSON diagnostics for a single configured environment: $setting, failure=$failure',
+  async ({setting, failure}) => {
+    await inTemporaryDirectory(async (directory) => {
+      await writeFile(
+        resolvePath(directory, 'shopify.theme.toml'),
+        `[environments.first]\npath = ${JSON.stringify(directory)}\n${setting}\n`,
+      )
+      const {loadEnvironment} = await import('@shopify/cli-kit/node/environments')
+      const actual = await vi.importActual<typeof import('@shopify/cli-kit/node/environments')>(
+        '@shopify/cli-kit/node/environments',
+      )
+      vi.mocked(loadEnvironment).mockImplementation((environment, filename, options) =>
+        actual.loadEnvironment(environment, filename, {...options, from: directory}),
+      )
+      vi.mocked(themeCheckRun).mockResolvedValue({offenses: [], theme: [], config: {} as never})
+      if (failure) vi.mocked(themeCheckRun).mockRejectedValueOnce(new Error('Check failed'))
+      const config = await configuration()
+      const previousExitCode = process.exitCode
+      process.exitCode = 0
+      try {
+        await withCapturedStandardStreams(async ({stdout, stderr}) => {
+          const argv = ['-e', 'first']
+          await runWithCommandEventsForCommand(argv, () => new Check(argv, config).run())
+
+          expect(JSON.parse(stdout())).toEqual({
+            environments: [
+              failure
+                ? {environment: 'first', error: {type: 'abort', message: 'Check failed'}}
+                : {environment: 'first', result: emptyResult},
+            ],
+          })
+          await vi.waitFor(() => expect(stderr()).not.toBe(''))
+          const events = stderr()
+            .trim()
+            .split('\n')
+            .map((line) => JSON.parse(line))
+          expect(events).toContainEqual(
+            expect.objectContaining({
+              type: 'diagnostic',
+              level: 'info',
+              message: expect.stringContaining('Using applicable flags from first environment:'),
+            }),
+          )
+          if (failure) {
+            expect(events).toContainEqual(
+              expect.objectContaining({type: 'diagnostic', level: 'error', code: 'theme-environment-failed'}),
+            )
+          }
+        })
+        expect(process.exitCode).toBe(failure ? 1 : 0)
+      } finally {
+        process.exitCode = previousExitCode
+      }
+    })
+  },
+)
+
+class LifecycleCheck extends Check {
+  execute(): Promise<void> {
+    return this._run<void>()
+  }
+}
+
+test.each(
+  [
+    {setting: 'json = true', invalidFlag: 'fail-level = "bogus"', message: '--fail-level', textOverride: false},
+    {setting: 'output = "json"', invalidFlag: 'fail-level = "bogus"', message: '--fail-level', textOverride: false},
+    {setting: 'json = true', invalidFlag: 'init = true', message: '--init', textOverride: false},
+    {setting: 'output = "json"', invalidFlag: 'fail-level = "bogus"', message: '--fail-level', textOverride: true},
+  ].flatMap((flags) => ['first', 'default'].map((environment) => ({...flags, environment}))),
+)(
+  'uses the requested format for environment parsing errors: $environment, $setting, $invalidFlag, textOverride=$textOverride',
+  async ({setting, invalidFlag, message, environment, textOverride}) => {
+    await inTemporaryDirectory(async (directory) => {
+      await writeFile(
+        resolvePath(directory, 'shopify.theme.toml'),
+        `[environments.${environment}]\n${setting}\n${invalidFlag}\n`,
+      )
+      const environments = await import('@shopify/cli-kit/node/environments')
+      const actual = await vi.importActual<typeof environments>('@shopify/cli-kit/node/environments')
+      vi.mocked(environments.loadEnvironment).mockImplementation(actual.loadEnvironment)
+      vi.mocked(environments.environmentFilePath).mockImplementation(actual.environmentFilePath)
+      vi.spyOn(Check.prototype as unknown as {init(): Promise<unknown>}, 'init').mockResolvedValue(undefined)
+      vi.spyOn(process, 'exit').mockImplementation(() => undefined as never)
+      const config = await configuration()
+      const argv = [
+        '--path',
+        directory,
+        ...(environment === 'default' ? [] : ['--environment', environment]),
+        ...(textOverride ? ['--output=text'] : []),
+      ]
+
+      await withCapturedStandardStreams(async ({stdout, stderr}) => {
+        await runWithCommandEventsForCommand(argv, () => new LifecycleCheck(argv, config).execute())
+
+        if (textOverride) {
+          expect(stdout()).toBe('')
+          expect(stderr()).toContain(message)
+        } else {
+          expect(JSON.parse(stdout())).toEqual({
+            error: expect.objectContaining({type: 'abort', message: expect.stringContaining(message)}),
+          })
+          expect(stderr()).toBe('')
+        }
+      })
+      expect(process.exit).toHaveBeenCalledWith(2)
+      expect(themeCheckRun).not.toHaveBeenCalled()
+    })
+  },
+)
+
+test.each([['--output=json'], ['-o', 'json']])(
+  'uses the standard JSON error envelope with an outer text context for %j',
+  async (...flags) => {
+    const config = await configuration()
+    vi.spyOn(Check.prototype as unknown as {init(): Promise<unknown>}, 'init').mockResolvedValue(undefined)
+    vi.spyOn(process, 'exit').mockImplementation(() => undefined as never)
+    await withCapturedStandardStreams(async ({stdout}) => {
+      const argv = [...flags, '--version']
+      await runWithCommandEventsForCommand(argv, () => new LifecycleCheck(argv, config).execute())
+      expect(JSON.parse(stdout())).toEqual({
+        error: expect.objectContaining({type: 'abort', message: expect.any(String)}),
+      })
+    })
+    expect(process.exit).toHaveBeenCalledWith(2)
+    expect(themeCheckRun).not.toHaveBeenCalled()
+  },
+)
+
+test('does not write a validation result before a requested correction fails', async () => {
+  const checkService = await import('../../services/check.js')
+  vi.spyOn(checkService, 'performAutoFixes').mockRejectedValue(new Error('Unable to write corrected file'))
+  vi.mocked(themeCheckRun).mockResolvedValue({offenses: [offense], theme: [], config: {} as never})
+  await inTemporaryDirectory(async (directory) => {
+    const config = await configuration()
+    await withCapturedStandardStreams(async ({stdout}) => {
+      await expect(new Check([`--path=${directory}`, '--json', '--auto-correct'], config).run()).rejects.toThrow(
+        'Unable to write corrected file',
+      )
+      expect(stdout()).toBe('')
+    })
+  })
+})
diff --git a/packages/theme/src/cli/commands/theme/check.ts b/packages/theme/src/cli/commands/theme/check.ts
index 5921f6ba370..bfe02ead318 100644
--- a/packages/theme/src/cli/commands/theme/check.ts
+++ b/packages/theme/src/cli/commands/theme/check.ts
@@ -1,32 +1,35 @@
 import ThemeCommand, {RequiredFlags} from '../../utilities/theme-command.js'
 import {
-  formatOffensesJson,
-  formatSummary,
+  checkTheme,
   initConfig,
   outputActiveChecks,
   outputActiveConfig,
   performAutoFixes,
-  renderOffensesText,
-  sortOffenses,
-  isExtendedWriteStream,
   handleExit,
-  withThemeCheckConfigErrorHandling,
+  themeCheckHasBlockingIssues,
   type FailLevel,
 } from '../../services/check.js'
+import {renderThemeCheckResult, encodeThemeCheckResult} from '../../services/check/result.js'
+import {themeCheckJsonOutputSchema} from '../../services/check/types.js'
 import {themeFlags} from '../../flags.js'
+import {runWithCommandEvents, renderCommandEventAsJson} from '@shopify/cli-kit/node/command-events'
 import {Flags} from '@oclif/core'
-import {globalFlags} from '@shopify/cli-kit/node/cli'
-import {outputResult, outputDebug} from '@shopify/cli-kit/node/output'
-import {renderInfo, renderSuccess} from '@shopify/cli-kit/node/ui'
-import {themeCheckRun, LegacyIdentifiers} from '@shopify/theme-check-node'
+import {globalFlags, jsonFlag} from '@shopify/cli-kit/node/cli'
+import {outputResult} from '@shopify/cli-kit/node/output'
+import {LegacyIdentifiers} from '@shopify/theme-check-node'
 import {findPathUp} from '@shopify/cli-kit/node/fs'
 import {moduleDirectory, joinPath} from '@shopify/cli-kit/node/path'
 import {getPackageVersion} from '@shopify/cli-kit/node/node-package-manager'
 import {InferredFlags} from '@oclif/core/interfaces'
 import {AdminSession} from '@shopify/cli-kit/node/session'
+import type {ThemeEnvironmentResult} from '../../services/json-output/schema.js'
 
 type CheckFlags = InferredFlags<typeof Check.flags>
 export default class Check extends ThemeCommand {
+  static get jsonOutputSchema() {
+    return themeCheckJsonOutputSchema
+  }
+
   static summary = 'Validate the theme.'
 
   static descriptionWithMarkdown = `Calls and runs [Theme Check](https://shopify.dev/docs/themes/tools/theme-check) to analyze your theme code for errors and to ensure that it follows theme and Liquid best practices. [Learn more about the checks that Theme Check runs.](https://shopify.dev/docs/themes/tools/theme-check/checks)`
@@ -35,6 +38,8 @@ export default class Check extends ThemeCommand {
 
   static flags = {
     ...globalFlags,
+    ...jsonFlag,
+    json: Flags.boolean({...jsonFlag.json, env: 'SHOPIFY_FLAG_JSON', exclusive: ['init', 'version', 'print', 'list']}),
     path: themeFlags.path,
     'auto-correct': Flags.boolean({
       char: 'a',
@@ -92,7 +97,7 @@ export default class Check extends ThemeCommand {
 
   static multiEnvironmentsFlags: RequiredFlags = ['path']
 
-  async command(flags: CheckFlags, _session: AdminSession, multiEnvironment: boolean): Promise<void> {
+  async command(flags: CheckFlags, _session: AdminSession, multiEnvironment: boolean) {
     // Its not clear to typescript that path will always be defined
     const path = flags.path
     const environment = flags.environment?.[0]
@@ -139,59 +144,58 @@ export default class Check extends ThemeCommand {
       return
     }
 
-    const {offenses, theme} = await runThemeCheck(path, flags.output, config, environment)
+    const output = await checkTheme(path, config, environment)
+    const {offenses, theme} = output
+    const json = flags.json || flags.output === 'json'
+    const valid = !themeCheckHasBlockingIssues(offenses, flags['fail-level'] as FailLevel)
+    if (!json) renderThemeCheckResult({...output, valid}, flags.output, path, environment)
 
     if (flags['auto-correct']) {
       await performAutoFixes(theme, offenses)
     }
 
-    if (!multiEnvironment) {
-      return handleExit(offenses, flags['fail-level'] as FailLevel)
+    if (json && !multiEnvironment) renderThemeCheckResult({...output, valid}, 'json', path, environment)
+
+    if (json) {
+      if (!valid) process.exitCode = 1
+      return {files: output.result, valid}
     }
+    if (!multiEnvironment) return handleExit(offenses, flags['fail-level'] as FailLevel)
   }
-}
-
-export async function runThemeCheck(path: string, outputFormat: string, config?: string, environment?: string) {
-  const {offenses, theme} = await withThemeCheckConfigErrorHandling(config, () =>
-    themeCheckRun(path, config, (message) => {
-      if (process.env.SHOPIFY_TMP_FLAG_DEBUG) {
-        outputDebug(message)
-      }
-    }),
-  )
-
-  const offensesByFile = sortOffenses(offenses)
 
-  if (outputFormat === 'text') {
-    renderOffensesText(offensesByFile, path, theme, environment)
-
-    // Use renderSuccess when theres no offenses
-    const render = offenses.length ? renderInfo : renderSuccess
-
-    render({
-      headline: environment ? `[${environment}] Theme Check Summary.` : 'Theme Check Summary.',
-      body: formatSummary(offenses, offensesByFile, theme),
-    })
+  protected async _run<T>(): Promise<T> {
+    const separatorIndex = this.argv.indexOf('--')
+    const argv = separatorIndex < 0 ? this.argv : this.argv.slice(0, separatorIndex)
+    const outputIndex = argv.findLastIndex((arg) => /^(?:--output(?:=|$)|-o)/.test(arg))
+    const output =
+      outputIndex < 0 ? process.env.SHOPIFY_FLAG_OUTPUT : argv[outputIndex]!.replace(/^(?:--output=|-o=?)/, '')
+    const legacyJson =
+      output === 'json' || ((output === '--output' || output === '') && argv[outputIndex + 1] === 'json')
+    if (legacyJson && !argv.includes('--json')) {
+      // The legacy format flag must also select CLI Kit's JSON error and side-event context.
+      this.argv = [...argv, '--json', ...(separatorIndex < 0 ? [] : this.argv.slice(separatorIndex))]
+    }
+    if (legacyJson) {
+      // The CLI launcher may have selected text events before the legacy flag was normalized.
+      return runWithCommandEvents({outputMode: 'json', sink: renderCommandEventAsJson}, () => super._run<T>())
+    }
+    return super._run<T>()
   }
 
-  if (outputFormat === 'json') {
-    /**
-     * Workaround:
-     * Force stdout to be blocking so that the JSON output is not broken when piped to another process.
-     * ie: ` | jq .`
-     * It turns out that console.log is technically asynchronous, and when we call process.exit(),
-     * node doesn't wait on all the output being sent to stdout and instead closes the process immediately
-     *
-     * https://github.com/pnp/cli-microsoft365/issues/1266#issuecomment-727254264
-     *
-     */
-    const stdout = process.stdout
-    if (isExtendedWriteStream(stdout)) {
-      stdout._handle.setBlocking(true)
-    }
+  protected collectsEnvironmentResults(flags: Partial<CheckFlags>): boolean {
+    return (
+      !flags.init && !flags.version && !flags.print && !flags.list && (Boolean(flags.json) || flags.output === 'json')
+    )
+  }
 
-    outputResult(JSON.stringify(formatOffensesJson(offensesByFile, environment)))
+  protected renderEnvironmentResults(environments: ThemeEnvironmentResult[]): void {
+    outputResult(encodeThemeCheckResult({environments}))
   }
+}
 
-  return {offenses, theme}
+// Compatibility adapter for theme push, which still presents check results as text.
+export async function runThemeCheck(path: string, outputFormat: string, config?: string, environment?: string) {
+  const result = await checkTheme(path, config, environment)
+  renderThemeCheckResult(result, outputFormat, path, environment)
+  return {offenses: result.offenses, theme: result.theme}
 }
diff --git a/packages/theme/src/cli/services/check.ts b/packages/theme/src/cli/services/check.ts
index 154ce4079da..dda9e9b1819 100644
--- a/packages/theme/src/cli/services/check.ts
+++ b/packages/theme/src/cli/services/check.ts
@@ -1,10 +1,12 @@
+import {ThemeCheckResult} from './check/types.js'
 import {fileExists, writeFile} from '@shopify/cli-kit/node/fs'
-import {outputResult, outputInfo, outputSuccess} from '@shopify/cli-kit/node/output'
+import {outputResult, outputInfo, outputSuccess, outputDebug} from '@shopify/cli-kit/node/output'
 import {joinPath, resolvePath} from '@shopify/cli-kit/node/path'
 import {renderInfo} from '@shopify/cli-kit/node/ui'
 import {uniq} from '@shopify/cli-kit/common/array'
 import {AbortError} from '@shopify/cli-kit/node/error'
 import {
+  themeCheckRun,
   Severity,
   applyFixToString,
   autofix,
@@ -21,24 +23,6 @@ type OffenseMap = Record<string, Offense[]>
 /** The contents of every theme file, keyed by its normalized uri. */
 type ThemeSourcesByUri = Map<string, string>
 
-interface TransformedOffense {
-  check: string
-  severity: string
-  start_row: number
-  start_column: number
-  end_row: number
-  end_column: number
-  message: string
-}
-
-interface TransformedOffenseMap {
-  path: string
-  offenses: TransformedOffense[]
-  errorCount: number
-  warningCount: number
-  infoCount: number
-}
-
 type SeverityCounts = Partial<{
   [Severity.ERROR]: number
   [Severity.WARNING]: number
@@ -58,7 +42,7 @@ function isMissingThemeCheckConfigFile(error: unknown, configPath: string) {
   )
 }
 
-export async function withThemeCheckConfigErrorHandling<T>(
+async function withThemeCheckConfigErrorHandling<T>(
   configPath: string | undefined,
   operation: () => Promise<T>,
 ): Promise<T> {
@@ -87,7 +71,7 @@ function failLevelToSeverity(failLevel: FailLevel): Severity | undefined {
   }
 }
 
-function severityToLabel(severity: Severity) {
+function severityToLabel(severity: Severity): 'error' | 'warning' | 'info' {
   switch (severity) {
     case Severity.ERROR:
       return 'error'
@@ -248,7 +232,7 @@ export function renderOffensesText(
   })
 }
 
-export function formatOffensesJson(offensesByFile: OffenseMap, environment?: string): TransformedOffenseMap[] {
+export function formatOffensesJson(offensesByFile: OffenseMap, environment?: string): ThemeCheckResult {
   return Object.entries(offensesByFile).map(([path, offenses]) => {
     const transformedOffenses = offenses.map((offense: Offense) => {
       return {
@@ -279,13 +263,12 @@ export function formatOffensesJson(offensesByFile: OffenseMap, environment?: str
  * Handles the process exit based on the offenses and fail level.
  */
 export function handleExit(offenses: Offense[], failLevel: FailLevel) {
-  // If there is no fail level set, exit with 0
-  if (!failLevel) process.exit(0)
-
-  const failSeverity = failLevelToSeverity(failLevel)
-  const shouldFail = failSeverity !== undefined && offenses.some((offense) => offense.severity <= failSeverity)
+  process.exit(themeCheckHasBlockingIssues(offenses, failLevel) ? 1 : 0)
+}
 
-  process.exit(shouldFail ? 1 : 0)
+export function themeCheckHasBlockingIssues(offenses: Offense[], failLevel: FailLevel): boolean {
+  const failSeverity = failLevel ? failLevelToSeverity(failLevel) : undefined
+  return failSeverity !== undefined && offenses.some((offense) => offense.severity <= failSeverity)
 }
 
 /**
@@ -416,3 +399,13 @@ export function isExtendedWriteStream(stream: NodeJS.WriteStream): stream is Ext
     typeof (stream as HandleWithSetBlocking)._handle.setBlocking === 'function'
   )
 }
+
+export async function checkTheme(path: string, config?: string, environment?: string) {
+  const {offenses, theme} = await withThemeCheckConfigErrorHandling(config, () =>
+    themeCheckRun(path, config, (message) => {
+      if (process.env.SHOPIFY_TMP_FLAG_DEBUG) outputDebug(message)
+    }),
+  )
+  const result = formatOffensesJson(sortOffenses(offenses), environment)
+  return {result, offenses, theme}
+}
diff --git a/packages/theme/src/cli/services/check/result.ts b/packages/theme/src/cli/services/check/result.ts
new file mode 100644
index 00000000000..420dd25284f
--- /dev/null
+++ b/packages/theme/src/cli/services/check/result.ts
@@ -0,0 +1,50 @@
+import {themeCheckJsonOutputSchema, type ThemeCheckResult} from './types.js'
+import {formatSummary, renderOffensesText, sortOffenses, isExtendedWriteStream} from '../check.js'
+import {outputResult} from '@shopify/cli-kit/node/output'
+import {renderInfo, renderSuccess} from '@shopify/cli-kit/node/ui'
+import {type Offense, type Theme} from '@shopify/theme-check-node'
+
+export function encodeThemeCheckResult(result: unknown): string {
+  // Keep the legacy output option compact while encoding the agreed object contract.
+  return JSON.stringify(JSON.parse(themeCheckJsonOutputSchema.encode(result)))
+}
+
+export function renderThemeCheckResult(
+  {result, offenses, theme, valid}: {result: ThemeCheckResult; offenses: Offense[]; theme: Theme; valid?: boolean},
+  outputFormat: string,
+  path: string,
+  environment?: string,
+): void {
+  const offensesByFile = sortOffenses(offenses)
+
+  if (outputFormat === 'text') {
+    renderOffensesText(offensesByFile, path, theme, environment)
+
+    // Use renderSuccess when theres no offenses
+    const render = offenses.length ? renderInfo : renderSuccess
+
+    render({
+      headline: environment ? `[${environment}] Theme Check Summary.` : 'Theme Check Summary.',
+      body: formatSummary(offenses, offensesByFile, theme),
+    })
+  }
+
+  if (outputFormat === 'json') {
+    /**
+     * Workaround:
+     * Force stdout to be blocking so that the JSON output is not broken when piped to another process.
+     * ie: ` | jq .`
+     * It turns out that console.log is technically asynchronous, and when we call process.exit(),
+     * node doesn't wait on all the output being sent to stdout and instead closes the process immediately
+     *
+     * https://github.com/pnp/cli-microsoft365/issues/1266#issuecomment-727254264
+     *
+     */
+    const stdout = process.stdout
+    if (isExtendedWriteStream(stdout)) {
+      stdout._handle.setBlocking(true)
+    }
+
+    outputResult(encodeThemeCheckResult(valid === undefined ? result : {files: result, valid}))
+  }
+}
diff --git a/packages/theme/src/cli/services/check/types.ts b/packages/theme/src/cli/services/check/types.ts
new file mode 100644
index 00000000000..7df2c5aec5e
--- /dev/null
+++ b/packages/theme/src/cli/services/check/types.ts
@@ -0,0 +1,76 @@
+import {defineThemeJsonOutputSchema} from '../json-output/schema.js'
+import {zod} from '@shopify/cli-kit/node/schema'
+import {isAbsolutePath} from '@shopify/cli-kit/node/path'
+// Native JSON paths must preserve Windows separators instead of pathe normalization.
+// eslint-disable-next-line no-restricted-imports
+import {resolve as resolvePath} from 'node:path'
+
+const ThemeCheckIssueSchema = zod
+  .object({
+    filePath: zod.string().refine(isAbsolutePath).describe('The absolute native path of the file.'),
+    check: zod.string(),
+    severity: zod.enum(['error', 'warning', 'info']),
+    startRow: zod.number().int().nonnegative().describe('The zero-based starting line.'),
+    startColumn: zod.number().int().nonnegative().describe('The zero-based starting column.'),
+    endRow: zod.number().int().nonnegative().describe('The zero-based ending line.'),
+    endColumn: zod.number().int().nonnegative().describe('The zero-based ending column.'),
+    message: zod.string(),
+  })
+  .strict()
+
+const ThemeCheckResultSchema = zod
+  .object({
+    valid: zod.boolean().describe('Whether the validation passes the selected blocking policy.'),
+    issues: zod.array(ThemeCheckIssueSchema),
+    errorCount: zod.number().int().nonnegative(),
+    warningCount: zod.number().int().nonnegative(),
+    infoCount: zod.number().int().nonnegative(),
+  })
+  .strict()
+
+/** The Theme Check service model used by text rendering and compatibility callers. */
+export type ThemeCheckResult = {
+  environment?: string
+  path: string
+  offenses: {
+    check: string
+    severity: 'error' | 'warning' | 'info'
+    start_row: number
+    start_column: number
+    end_row: number
+    end_column: number
+    message: string
+  }[]
+  errorCount: number
+  warningCount: number
+  infoCount: number
+}[]
+
+export const themeCheckJsonOutputSchema = defineThemeJsonOutputSchema({
+  name: 'ThemeCheckResult',
+  schema: ThemeCheckResultSchema,
+  definitions: {ThemeCheckIssue: ThemeCheckIssueSchema},
+  project: (value) => {
+    const {files, valid} = Array.isArray(value)
+      ? {files: value as ThemeCheckResult, valid: undefined}
+      : (value as {files: ThemeCheckResult; valid: boolean})
+    return {
+      valid: valid ?? files.every((file) => file.errorCount === 0),
+      issues: files.flatMap((file) =>
+        file.offenses.map((offense) => ({
+          filePath: resolvePath(file.path),
+          check: offense.check,
+          severity: offense.severity,
+          startRow: offense.start_row,
+          startColumn: offense.start_column,
+          endRow: offense.end_row,
+          endColumn: offense.end_column,
+          message: offense.message,
+        })),
+      ),
+      errorCount: files.reduce((count, file) => count + file.errorCount, 0),
+      warningCount: files.reduce((count, file) => count + file.warningCount, 0),
+      infoCount: files.reduce((count, file) => count + file.infoCount, 0),
+    }
+  },
+})
diff --git a/packages/theme/src/cli/utilities/theme-command.ts b/packages/theme/src/cli/utilities/theme-command.ts
index bdfe58a5c82..cd84041ab06 100644
--- a/packages/theme/src/cli/utilities/theme-command.ts
+++ b/packages/theme/src/cli/utilities/theme-command.ts
@@ -25,7 +25,12 @@ import {AbortController} from '@shopify/cli-kit/node/abort'
 import {AbortError, BugError, ExternalError, FatalError} from '@shopify/cli-kit/node/error'
 import {recordEvent, compileData} from '@shopify/cli-kit/node/analytics'
 import {addPublicMetadata, addSensitiveMetadata} from '@shopify/cli-kit/node/metadata'
-import {commandEventOutputMode, emitCommandEvent} from '@shopify/cli-kit/node/command-events'
+import {
+  commandEventOutputMode,
+  emitCommandEvent,
+  renderCommandEventAsJson,
+  runWithCommandEvents,
+} from '@shopify/cli-kit/node/command-events'
 import {outputDebug, outputResult} from '@shopify/cli-kit/node/output'
 import {jsonOutputEnabled} from '@shopify/cli-kit/node/environment'
 import {cwd, joinPath, resolvePath} from '@shopify/cli-kit/node/path'
@@ -98,7 +103,7 @@ export default abstract class ThemeCommand extends Command {
     const commandRequiresAuth = 'password' in klass.flags
 
     const environments = (Array.isArray(flags.environment) ? flags.environment : [flags.environment]).filter(Boolean)
-    const collectResults = hasExplicitEnvironment && this.collectsEnvironmentResults(flags)
+    let collectResults = hasExplicitEnvironment && this.collectsEnvironmentResults(flags)
 
     // Check if store flag is required by the command
     const storeIsRequired =
@@ -142,38 +147,46 @@ export default abstract class ThemeCommand extends Command {
     }
 
     const environmentsMap = await this.loadEnvironments(environments, flags, flagsWithoutDefaults)
-    const validationResults = await this.validateEnvironments(
-      environmentsMap,
-      requiredFlags ?? [],
-      commandRequiresAuth,
-      collectResults,
-    )
+    collectResults ||= Array.from(environmentsMap.values()).some(({flags}) => this.collectsEnvironmentResults(flags))
+    const runEnvironments = async () => {
+      const validationResults = await this.validateEnvironments(
+        environmentsMap,
+        requiredFlags ?? [],
+        commandRequiresAuth,
+        collectResults,
+      )
+
+      if (this.requiresEnvironmentConfirmation(flags)) {
+        const confirmed = await this.showConfirmation(this.constructor.name, requiredFlags ?? [], validationResults)
+        if (!confirmed) {
+          if (collectResults)
+            this.renderEnvironmentResults(
+              environments.map((environment) => ({environment, result: {status: 'cancelled'}})),
+            )
+          return
+        }
+      }
 
-    if (this.requiresEnvironmentConfirmation(flags)) {
-      const confirmed = await this.showConfirmation(this.constructor.name, requiredFlags ?? [], validationResults)
-      if (!confirmed) {
-        if (collectResults)
-          this.renderEnvironmentResults(
-            environments.map((environment) => ({environment, result: {status: 'cancelled'}})),
+      const results = await this.runConcurrent(validationResults.valid, collectResults)
+      if (collectResults) {
+        const entries: ThemeEnvironmentResult[] = environments.map((environment) => {
+          const invalid = validationResults.invalid.find((entry) => entry.environment === environment)
+          return (
+            results.get(environment) ?? {
+              environment,
+              error: {type: 'abort', message: invalid?.reason ?? 'The environment did not return a result.'},
+            }
           )
-        return
+        })
+        this.renderEnvironmentResults(entries)
+        if (entries.some((entry) => 'error' in entry)) process.exitCode = 1
       }
     }
 
-    const results = await this.runConcurrent(validationResults.valid, collectResults)
-    if (collectResults) {
-      const entries: ThemeEnvironmentResult[] = environments.map((environment) => {
-        const invalid = validationResults.invalid.find((entry) => entry.environment === environment)
-        return (
-          results.get(environment) ?? {
-            environment,
-            error: {type: 'abort', message: invalid?.reason ?? 'The environment did not return a result.'},
-          }
-        )
-      })
-      this.renderEnvironmentResults(entries)
-      if (entries.some((entry) => 'error' in entry)) process.exitCode = 1
+    if (collectResults && commandEventOutputMode() !== 'json') {
+      return runWithCommandEvents({outputMode: 'json', sink: renderCommandEventAsJson}, runEnvironments)
     }
+    return runEnvironments()
   }
 
   protected collectsEnvironmentResults(flags: FlagValues): boolean {