diff --git a/.chronus/changes/http-server-csharp-converters-on-ef-2026-8-5.md b/.chronus/changes/http-server-csharp-converters-on-ef-2026-8-5.md
new file mode 100644
index 00000000000..bb40d882404
--- /dev/null
+++ b/.chronus/changes/http-server-csharp-converters-on-ef-2026-8-5.md
@@ -0,0 +1,9 @@
+---
+changeKind: internal
+packages:
+  - "@typespec/http-server-csharp"
+---
+
+Generate the JSON converter helpers with the emitter framework's `JsonConverter` component
+
+`TimeSpanDurationConverter`, `Base64UrlJsonConverter` and the Unix epoch converters were raw string templates. The generated classes are unchanged apart from an explicit `using System;` that was previously implicit.
diff --git a/packages/http-server-csharp/src/components/serialization/base64-url-json-converter.tsx b/packages/http-server-csharp/src/components/serialization/base64-url-json-converter.tsx
index c90d6dd2dd6..ef1391f86c3 100644
--- a/packages/http-server-csharp/src/components/serialization/base64-url-json-converter.tsx
+++ b/packages/http-server-csharp/src/components/serialization/base64-url-json-converter.tsx
@@ -1,5 +1,6 @@
 import { code, type Children } from "@alloy-js/core";
-import { Namespace } from "@alloy-js/csharp";
+import { DocSummary, Namespace } from "@alloy-js/csharp";
+import { JsonConverter } from "@typespec/emitter-framework/csharp";
 import { CSharpFile } from "../csharp-file.jsx";
 
 /**
@@ -8,17 +9,32 @@ import { CSharpFile } from "../csharp-file.jsx";
  */
 export function Base64UrlJsonConverter(): Children {
   return (
-    <CSharpFile
-      path="Base64UrlJsonConverter.cs"
-      using={["System.Text.Json", "System.Text.Json.Serialization"]}
-    >
+    <CSharpFile path="Base64UrlJsonConverter.cs">
       <Namespace name="TypeSpec.Helpers.JsonConverters">
-        {code`
-          /// <summary>
-          /// System.Text.Json converter for the properties using Base64Url encoding
-          /// </summary>
-          public class Base64UrlJsonConverter : JsonConverter<byte[]>
-          {
+        <JsonConverter
+          name="Base64UrlJsonConverter"
+          csharpType="byte[]"
+          public
+          sealed={false}
+          doc={
+            <DocSummary>
+              System.Text.Json converter for the properties using Base64Url encoding
+            </DocSummary>
+          }
+          readReturns="byte[]?"
+          decodeAndReturn={(reader, typeToConvert) => code`
+            if (${typeToConvert} != typeof(byte[]))
+              throw new ArgumentException($"Cannot apply converter {this.GetType().FullName} to type {${typeToConvert}.FullName}");
+            var value = ${reader}.GetString();
+            if (string.IsNullOrWhiteSpace(value))
+              return null;
+            return Convert.FromBase64String(Pad(value.Replace('-', '+').Replace('_', '/')));
+          `}
+          encodeAndWrite={(writer, value) => code`
+            ${writer}.WriteStringValue(Convert.ToBase64String(${value}).TrimEnd('=').Replace('+', '-').Replace('/', '_'));
+          `}
+        >
+          {code`
             /// <summary>
             /// Adds padding to the input
             /// </summary>
@@ -26,30 +42,15 @@ export function Base64UrlJsonConverter(): Children {
             /// <returns> the padded string </returns>
             private static string Pad(string input)
             {
-              var count = 3 - ((input.Length + 3) % 4);
-              if (count == 0)
-              {
-                return input;
-              }
-              return $"{input}{new string('=', count)}";
-            }
-
-            public override byte[]? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
-            {
-              if (typeToConvert != typeof(byte[]))
-                throw new ArgumentException($"Cannot apply converter {this.GetType().FullName} to type {typeToConvert.FullName}");
-              var value = reader.GetString();
-              if (string.IsNullOrWhiteSpace(value))
-                return null;
-              return Convert.FromBase64String(Pad(value.Replace('-', '+').Replace('_', '/')));
+                var count = 3 - ((input.Length + 3) % 4);
+                if (count == 0)
+                {
+                    return input;
+                }
+                return $"{input}{new string('=', count)}";
             }
-
-            public override void Write(Utf8JsonWriter writer, byte[] value, JsonSerializerOptions options)
-            {
-              writer.WriteStringValue(Convert.ToBase64String(value).TrimEnd('=').Replace('+', '-').Replace('/', '_'));
-            }
-          }
-        `}
+          `}
+        </JsonConverter>
       </Namespace>
     </CSharpFile>
   );
diff --git a/packages/http-server-csharp/src/components/serialization/time-span-duration-converter.tsx b/packages/http-server-csharp/src/components/serialization/time-span-duration-converter.tsx
index b38dd602aab..6a607de3a20 100644
--- a/packages/http-server-csharp/src/components/serialization/time-span-duration-converter.tsx
+++ b/packages/http-server-csharp/src/components/serialization/time-span-duration-converter.tsx
@@ -1,5 +1,6 @@
 import { code, type Children } from "@alloy-js/core";
-import { Namespace } from "@alloy-js/csharp";
+import { DocSummary, Namespace } from "@alloy-js/csharp";
+import { JsonConverter } from "@typespec/emitter-framework/csharp";
 import { CSharpFile } from "../csharp-file.jsx";
 
 /**
@@ -8,34 +9,27 @@ import { CSharpFile } from "../csharp-file.jsx";
  */
 export function TimeSpanDurationConverter(): Children {
   return (
-    <CSharpFile
-      path="TimeSpanDurationConverter.cs"
-      using={["System.Text.Json", "System.Text.Json.Serialization", "System.Xml"]}
-    >
+    <CSharpFile path="TimeSpanDurationConverter.cs" using={["System.Xml"]}>
       <Namespace name="TypeSpec.Helpers.JsonConverters">
-        {code`
-          /// <summary>
-          /// Converts between Json duration and .Net TimeSpan
-          /// </summary>
-          public class TimeSpanDurationConverter : JsonConverter<TimeSpan>
-          {
-            public override TimeSpan Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
-            {
-              if (typeToConvert != typeof(TimeSpan))
-                throw new ArgumentException($"Cannot apply converter {this.GetType().FullName} to type {typeToConvert.FullName}");
+        <JsonConverter
+          name="TimeSpanDurationConverter"
+          csharpType="TimeSpan"
+          public
+          sealed={false}
+          doc={<DocSummary>Converts between Json duration and .Net TimeSpan</DocSummary>}
+          decodeAndReturn={(reader, typeToConvert) => code`
+            if (${typeToConvert} != typeof(TimeSpan))
+              throw new ArgumentException($"Cannot apply converter {this.GetType().FullName} to type {${typeToConvert}.FullName}");
 
-              var value = reader.GetString();
-              if (string.IsNullOrWhiteSpace(value))
-                return TimeSpan.MinValue;
-              return XmlConvert.ToTimeSpan(value);
-            }
-
-            public override void Write(Utf8JsonWriter writer, TimeSpan value, JsonSerializerOptions options)
-            {
-              writer.WriteStringValue(XmlConvert.ToString(value));
-            }
-          }
-        `}
+            var value = ${reader}.GetString();
+            if (string.IsNullOrWhiteSpace(value))
+              return TimeSpan.MinValue;
+            return XmlConvert.ToTimeSpan(value);
+          `}
+          encodeAndWrite={(writer, value) => code`
+            ${writer}.WriteStringValue(XmlConvert.ToString(${value}));
+          `}
+        />
       </Namespace>
     </CSharpFile>
   );
diff --git a/packages/http-server-csharp/src/components/serialization/unix-epoch-date-time-converter.tsx b/packages/http-server-csharp/src/components/serialization/unix-epoch-date-time-converter.tsx
index 25e394684cf..df6bc85dc2b 100644
--- a/packages/http-server-csharp/src/components/serialization/unix-epoch-date-time-converter.tsx
+++ b/packages/http-server-csharp/src/components/serialization/unix-epoch-date-time-converter.tsx
@@ -1,5 +1,6 @@
 import { code, type Children } from "@alloy-js/core";
-import { Namespace } from "@alloy-js/csharp";
+import { DocSummary, Namespace } from "@alloy-js/csharp";
+import { JsonConverter } from "@typespec/emitter-framework/csharp";
 import { CSharpFile } from "../csharp-file.jsx";
 
 /**
@@ -9,60 +10,48 @@ import { CSharpFile } from "../csharp-file.jsx";
 export function UnixEpochDateTimeConverter(): Children {
   return (
     <>
-      <CSharpFile
-        path="UnixEpochDateTimeConverter.cs"
-        using={["System.Text.Json", "System.Text.Json.Serialization"]}
-      >
+      <CSharpFile path="UnixEpochDateTimeConverter.cs">
         <Namespace name="TypeSpec.Helpers.JsonConverters">
-          {code`
-            /// <summary>
-            /// Converts between an integer timestamp and a .Net DateTime
-            /// </summary>
-            public sealed class UnixEpochDateTimeConverter : JsonConverter<DateTime>
-            {
-              static readonly DateTime s_epoch = new DateTime(1970, 1, 1, 0, 0, 0);
-
-              public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
-              {
-                var formatted = reader.GetInt64()!;
-                return s_epoch.AddMilliseconds(formatted);
-              }
-
-              public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)
-              {
-                long unixTime = Convert.ToInt64((value - s_epoch).TotalMilliseconds);
-                writer.WriteNumberValue(unixTime);
-              }
-            }
-          `}
+          <JsonConverter
+            name="UnixEpochDateTimeConverter"
+            // `utcDateTime` maps to `DateTimeOffset`; this converter is the `DateTime` one.
+            csharpType="DateTime"
+            public
+            doc={<DocSummary>Converts between an integer timestamp and a .Net DateTime</DocSummary>}
+            decodeAndReturn={(reader) => code`
+              var formatted = ${reader}.GetInt64()!;
+              return s_epoch.AddMilliseconds(formatted);
+            `}
+            encodeAndWrite={(writer, value) => code`
+              long unixTime = Convert.ToInt64((${value} - s_epoch).TotalMilliseconds);
+              ${writer}.WriteNumberValue(unixTime);
+            `}
+          >
+            {code`static readonly DateTime s_epoch = new DateTime(1970, 1, 1, 0, 0, 0);`}
+          </JsonConverter>
         </Namespace>
       </CSharpFile>
-      <CSharpFile
-        path="UnixEpochDateTimeOffsetConverter.cs"
-        using={["System.Text.Json", "System.Text.Json.Serialization"]}
-      >
+      <CSharpFile path="UnixEpochDateTimeOffsetConverter.cs">
         <Namespace name="TypeSpec.Helpers.JsonConverters">
-          {code`
-            /// <summary>
-            /// Converts between a Unix TimeStamp and a .Net DateTimeOffset
-            /// </summary>
-            public sealed class UnixEpochDateTimeOffsetConverter : JsonConverter<DateTimeOffset>
-            {
-              static readonly DateTimeOffset s_epoch = new DateTimeOffset(1970, 1, 1, 0, 0, 0, TimeSpan.Zero);
-
-              public override DateTimeOffset Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
-              {
-                var formatted = reader.GetInt64()!;
-                return s_epoch.AddMilliseconds(formatted);
-              }
-
-              public override void Write(Utf8JsonWriter writer, DateTimeOffset value, JsonSerializerOptions options)
-              {
-                long unixTime = Convert.ToInt64((value - s_epoch).TotalMilliseconds);
-                writer.WriteNumberValue(unixTime);
-              }
+          <JsonConverter
+            name="UnixEpochDateTimeOffsetConverter"
+            // `DateTimeOffset` has no TypeSpec equivalent, so the C# type is given directly.
+            csharpType="DateTimeOffset"
+            public
+            doc={
+              <DocSummary>Converts between a Unix TimeStamp and a .Net DateTimeOffset</DocSummary>
             }
-          `}
+            decodeAndReturn={(reader) => code`
+              var formatted = ${reader}.GetInt64()!;
+              return s_epoch.AddMilliseconds(formatted);
+            `}
+            encodeAndWrite={(writer, value) => code`
+              long unixTime = Convert.ToInt64((${value} - s_epoch).TotalMilliseconds);
+              ${writer}.WriteNumberValue(unixTime);
+            `}
+          >
+            {code`static readonly DateTimeOffset s_epoch = new DateTimeOffset(1970, 1, 1, 0, 0, 0, TimeSpan.Zero);`}
+          </JsonConverter>
         </Namespace>
       </CSharpFile>
     </>
diff --git a/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/Base64UrlJsonConverter.cs b/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/Base64UrlJsonConverter.cs
index 31b7a3320aa..b391a1bfc9f 100644
--- a/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/Base64UrlJsonConverter.cs
+++ b/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/Base64UrlJsonConverter.cs
@@ -2,6 +2,7 @@
 // <auto-generated />
 #nullable enable
 
+using System;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
diff --git a/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/TimeSpanDurationConverter.cs b/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/TimeSpanDurationConverter.cs
index 78ea0937205..0202505f313 100644
--- a/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/TimeSpanDurationConverter.cs
+++ b/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/TimeSpanDurationConverter.cs
@@ -2,6 +2,7 @@
 // <auto-generated />
 #nullable enable
 
+using System;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 using System.Xml;
diff --git a/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/UnixEpochDateTimeConverter.cs b/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/UnixEpochDateTimeConverter.cs
index 1706e2aa02c..f04a52c2b09 100644
--- a/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/UnixEpochDateTimeConverter.cs
+++ b/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/UnixEpochDateTimeConverter.cs
@@ -2,6 +2,7 @@
 // <auto-generated />
 #nullable enable
 
+using System;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
diff --git a/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/UnixEpochDateTimeOffsetConverter.cs b/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/UnixEpochDateTimeOffsetConverter.cs
index c9bddfa3343..fee5f55fb7c 100644
--- a/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/UnixEpochDateTimeOffsetConverter.cs
+++ b/packages/http-server-csharp/test/snapshots/sample-service/generated/lib/UnixEpochDateTimeOffsetConverter.cs
@@ -2,6 +2,7 @@
 // <auto-generated />
 #nullable enable
 
+using System;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
@@ -14,7 +15,11 @@ public sealed class UnixEpochDateTimeOffsetConverter : JsonConverter<DateTimeOff
     {
         static readonly DateTimeOffset s_epoch = new DateTimeOffset(1970, 1, 1, 0, 0, 0, TimeSpan.Zero);
 
-        public override DateTimeOffset Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+        public override DateTimeOffset Read(
+            ref Utf8JsonReader reader,
+            Type typeToConvert,
+            JsonSerializerOptions options
+        )
         {
             var formatted = reader.GetInt64()!;
             return s_epoch.AddMilliseconds(formatted);