diff --git a/packages/http-client-csharp/emitter/src/lib/operation-converter.ts b/packages/http-client-csharp/emitter/src/lib/operation-converter.ts
index bada9905120..766c2b2866a 100644
--- a/packages/http-client-csharp/emitter/src/lib/operation-converter.ts
+++ b/packages/http-client-csharp/emitter/src/lib/operation-converter.ts
@@ -317,6 +317,14 @@ function updateMethodParameter(
   operationHttpParameter: SdkHttpParameter | SdkModelPropertyType,
   rootApiVersions: string[],
 ): void {
+  // for content type parameter
+  if (isContentType(operationHttpParameter)) {
+    methodParameter.type = fromSdkType(
+      sdkContext,
+      operationHttpParameter.type,
+      operationHttpParameter,
+    );
+  }
   methodParameter.serializedName = getNameInRequest(operationHttpParameter);
   methodParameter.location = getParameterLocation(operationHttpParameter);
   methodParameter.scope = getParameterScope(
diff --git a/packages/http-client-csharp/emitter/src/lib/type-converter.ts b/packages/http-client-csharp/emitter/src/lib/type-converter.ts
index f3a008ed668..7107cc7d4b1 100644
--- a/packages/http-client-csharp/emitter/src/lib/type-converter.ts
+++ b/packages/http-client-csharp/emitter/src/lib/type-converter.ts
@@ -307,7 +307,7 @@ function createEnumType(
     crossLanguageDefinitionId: sdkType.kind === "enum" ? sdkType.crossLanguageDefinitionId : "",
     valueType:
       sdkType.kind === "enum"
-        ? (fromSdkType(sdkContext, sdkType.valueType) as InputPrimitiveType)
+        ? fromSdkType(sdkContext, sdkType.valueType)
         : fromSdkBuiltInType(sdkContext, sdkType.valueType),
     values: values,
     // constantType.access, TODO - constant type now does not have access. TCGC will add it later
diff --git a/packages/http-client-csharp/emitter/test/Unit/operation-converter.test.ts b/packages/http-client-csharp/emitter/test/Unit/operation-converter.test.ts
index bf8958e71a9..ddaea32c419 100644
--- a/packages/http-client-csharp/emitter/test/Unit/operation-converter.test.ts
+++ b/packages/http-client-csharp/emitter/test/Unit/operation-converter.test.ts
@@ -390,6 +390,14 @@ describe("Operation Converter", () => {
         const method = root.clients[0].methods[0];
         ok(method);
 
+        const contentTypeMethodParam = method.parameters.find((p) => p.name === "contentType");
+        ok(contentTypeMethodParam, "Content-Type parameter should exist in service method");
+        strictEqual(
+          contentTypeMethodParam.type.kind,
+          "constant",
+          "Content-type should remain a constant type, not transformed to enum",
+        );
+
         // validate operation
         const operation = method.operation;
         ok(operation);
diff --git a/packages/http-client-csharp/generator/TestProjects/Local/Sample-TypeSpec/tspCodeModel.json b/packages/http-client-csharp/generator/TestProjects/Local/Sample-TypeSpec/tspCodeModel.json
index 43e7b9552c0..e68a2e721e8 100644
--- a/packages/http-client-csharp/generator/TestProjects/Local/Sample-TypeSpec/tspCodeModel.json
+++ b/packages/http-client-csharp/generator/TestProjects/Local/Sample-TypeSpec/tspCodeModel.json
@@ -4717,7 +4717,7 @@
               "name": "contentType",
               "serializedName": "Content-Type",
               "type": {
-                "$ref": "90"
+                "$ref": "86"
               },
               "location": "Header",
               "isApiVersion": false,
diff --git a/packages/http-client-csharp/generator/TestProjects/Spector/http/encode/bytes/tspCodeModel.json b/packages/http-client-csharp/generator/TestProjects/Spector/http/encode/bytes/tspCodeModel.json
index bf92ec111b2..38c893f0473 100644
--- a/packages/http-client-csharp/generator/TestProjects/Spector/http/encode/bytes/tspCodeModel.json
+++ b/packages/http-client-csharp/generator/TestProjects/Spector/http/encode/bytes/tspCodeModel.json
@@ -2278,7 +2278,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "21"
+                    "$ref": "19"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2398,7 +2398,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "25"
+                    "$ref": "23"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2519,7 +2519,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "29"
+                    "$ref": "27"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2641,7 +2641,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "33"
+                    "$ref": "31"
                   },
                   "location": "Header",
                   "isApiVersion": false,
diff --git a/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/json-merge-patch/tspCodeModel.json b/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/json-merge-patch/tspCodeModel.json
index 950f7f2562f..476b957e44c 100644
--- a/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/json-merge-patch/tspCodeModel.json
+++ b/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/json-merge-patch/tspCodeModel.json
@@ -876,7 +876,7 @@
               "name": "contentType",
               "serializedName": "Content-Type",
               "type": {
-                "$ref": "9"
+                "$ref": "5"
               },
               "location": "Header",
               "isApiVersion": false,
@@ -1033,7 +1033,7 @@
               "name": "contentType",
               "serializedName": "Content-Type",
               "type": {
-                "$ref": "15"
+                "$ref": "11"
               },
               "location": "Header",
               "isApiVersion": false,
diff --git a/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/media-type/tspCodeModel.json b/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/media-type/tspCodeModel.json
index 18576b03aa8..fcea8fff72f 100644
--- a/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/media-type/tspCodeModel.json
+++ b/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/media-type/tspCodeModel.json
@@ -265,7 +265,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "3"
+                    "$ref": "1"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -480,7 +480,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "11"
+                    "$ref": "9"
                   },
                   "location": "Header",
                   "isApiVersion": false,
diff --git a/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/multipart/tspCodeModel.json b/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/multipart/tspCodeModel.json
index 4732c4fe160..9c871c88404 100644
--- a/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/multipart/tspCodeModel.json
+++ b/packages/http-client-csharp/generator/TestProjects/Spector/http/payload/multipart/tspCodeModel.json
@@ -2084,7 +2084,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "5"
+                    "$ref": "3"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2198,7 +2198,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "9"
+                    "$ref": "7"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2312,7 +2312,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "13"
+                    "$ref": "11"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2426,7 +2426,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "17"
+                    "$ref": "15"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2540,7 +2540,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "21"
+                    "$ref": "19"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2654,7 +2654,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "25"
+                    "$ref": "23"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2768,7 +2768,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "29"
+                    "$ref": "27"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2882,7 +2882,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "33"
+                    "$ref": "31"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2996,7 +2996,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "37"
+                    "$ref": "35"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -3157,7 +3157,7 @@
                       "name": "contentType",
                       "serializedName": "Content-Type",
                       "type": {
-                        "$ref": "41"
+                        "$ref": "39"
                       },
                       "location": "Header",
                       "isApiVersion": false,
@@ -3318,7 +3318,7 @@
                           "name": "contentType",
                           "serializedName": "Content-Type",
                           "type": {
-                            "$ref": "45"
+                            "$ref": "43"
                           },
                           "location": "Header",
                           "isApiVersion": false,
@@ -3432,7 +3432,7 @@
                           "name": "contentType",
                           "serializedName": "Content-Type",
                           "type": {
-                            "$ref": "49"
+                            "$ref": "47"
                           },
                           "location": "Header",
                           "isApiVersion": false,
@@ -3546,7 +3546,7 @@
                           "name": "contentType",
                           "serializedName": "Content-Type",
                           "type": {
-                            "$ref": "53"
+                            "$ref": "51"
                           },
                           "location": "Header",
                           "isApiVersion": false,
@@ -3708,7 +3708,7 @@
                           "name": "contentType",
                           "serializedName": "Content-Type",
                           "type": {
-                            "$ref": "57"
+                            "$ref": "55"
                           },
                           "location": "Header",
                           "isApiVersion": false,
diff --git a/packages/http-client-csharp/generator/TestProjects/Spector/http/type/enum/extensible/tspCodeModel.json b/packages/http-client-csharp/generator/TestProjects/Spector/http/type/enum/extensible/tspCodeModel.json
index 5c38b68e159..0d029e9ad26 100644
--- a/packages/http-client-csharp/generator/TestProjects/Spector/http/type/enum/extensible/tspCodeModel.json
+++ b/packages/http-client-csharp/generator/TestProjects/Spector/http/type/enum/extensible/tspCodeModel.json
@@ -562,7 +562,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "20"
+                    "$ref": "18"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -674,7 +674,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "24"
+                    "$ref": "22"
                   },
                   "location": "Header",
                   "isApiVersion": false,
diff --git a/packages/http-client-csharp/generator/TestProjects/Spector/http/type/enum/fixed/tspCodeModel.json b/packages/http-client-csharp/generator/TestProjects/Spector/http/type/enum/fixed/tspCodeModel.json
index 81294dfe614..e3b49081a5a 100644
--- a/packages/http-client-csharp/generator/TestProjects/Spector/http/type/enum/fixed/tspCodeModel.json
+++ b/packages/http-client-csharp/generator/TestProjects/Spector/http/type/enum/fixed/tspCodeModel.json
@@ -444,7 +444,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "16"
+                    "$ref": "14"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -560,7 +560,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "20"
+                    "$ref": "18"
                   },
                   "location": "Header",
                   "isApiVersion": false,
diff --git a/packages/http-client-csharp/generator/TestProjects/Spector/http/type/property/nullable/tspCodeModel.json b/packages/http-client-csharp/generator/TestProjects/Spector/http/type/property/nullable/tspCodeModel.json
index 606d8272703..cd72d77e3c2 100644
--- a/packages/http-client-csharp/generator/TestProjects/Spector/http/type/property/nullable/tspCodeModel.json
+++ b/packages/http-client-csharp/generator/TestProjects/Spector/http/type/property/nullable/tspCodeModel.json
@@ -1576,7 +1576,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "7"
+                    "$ref": "5"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -1692,7 +1692,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "11"
+                    "$ref": "9"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2026,7 +2026,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "19"
+                    "$ref": "17"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2142,7 +2142,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "23"
+                    "$ref": "21"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2476,7 +2476,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "31"
+                    "$ref": "29"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2592,7 +2592,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "35"
+                    "$ref": "33"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2926,7 +2926,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "43"
+                    "$ref": "41"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -3042,7 +3042,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "47"
+                    "$ref": "45"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -3376,7 +3376,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "55"
+                    "$ref": "53"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -3492,7 +3492,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "59"
+                    "$ref": "57"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -3826,7 +3826,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "67"
+                    "$ref": "65"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -3942,7 +3942,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "71"
+                    "$ref": "69"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -4276,7 +4276,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "79"
+                    "$ref": "77"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -4392,7 +4392,7 @@
                   "serializedName": "Content-Type",
                   "doc": "content-type is application/merge-patch+json",
                   "type": {
-                    "$ref": "83"
+                    "$ref": "81"
                   },
                   "location": "Header",
                   "isApiVersion": false,
diff --git a/packages/http-client-csharp/generator/TestProjects/Spector/http/type/scalar/tspCodeModel.json b/packages/http-client-csharp/generator/TestProjects/Spector/http/type/scalar/tspCodeModel.json
index 7755a14604f..c5f20e56718 100644
--- a/packages/http-client-csharp/generator/TestProjects/Spector/http/type/scalar/tspCodeModel.json
+++ b/packages/http-client-csharp/generator/TestProjects/Spector/http/type/scalar/tspCodeModel.json
@@ -636,7 +636,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "7"
+                    "$ref": "5"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -905,7 +905,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "15"
+                    "$ref": "13"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -1174,7 +1174,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "23"
+                    "$ref": "21"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -1439,7 +1439,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "31"
+                    "$ref": "29"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -1784,7 +1784,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "39"
+                    "$ref": "37"
                   },
                   "location": "Header",
                   "isApiVersion": false,
@@ -2128,7 +2128,7 @@
                   "name": "contentType",
                   "serializedName": "Content-Type",
                   "type": {
-                    "$ref": "45"
+                    "$ref": "49"
                   },
                   "location": "Header",
                   "isApiVersion": false,
diff --git a/packages/http-client-csharp/generator/TestProjects/Spector/http/versioning/returnTypeChangedFrom/v1/tspCodeModel.json b/packages/http-client-csharp/generator/TestProjects/Spector/http/versioning/returnTypeChangedFrom/v1/tspCodeModel.json
index eafb3020517..44b9222e057 100644
--- a/packages/http-client-csharp/generator/TestProjects/Spector/http/versioning/returnTypeChangedFrom/v1/tspCodeModel.json
+++ b/packages/http-client-csharp/generator/TestProjects/Spector/http/versioning/returnTypeChangedFrom/v1/tspCodeModel.json
@@ -232,7 +232,7 @@
               "name": "contentType",
               "serializedName": "Content-Type",
               "type": {
-                "$ref": "10"
+                "$ref": "4"
               },
               "location": "Header",
               "isApiVersion": false,
diff --git a/packages/http-client-csharp/generator/TestProjects/Spector/http/versioning/returnTypeChangedFrom/v2/tspCodeModel.json b/packages/http-client-csharp/generator/TestProjects/Spector/http/versioning/returnTypeChangedFrom/v2/tspCodeModel.json
index b3c71751fc8..4efc88d0634 100644
--- a/packages/http-client-csharp/generator/TestProjects/Spector/http/versioning/returnTypeChangedFrom/v2/tspCodeModel.json
+++ b/packages/http-client-csharp/generator/TestProjects/Spector/http/versioning/returnTypeChangedFrom/v2/tspCodeModel.json
@@ -248,7 +248,7 @@
               "name": "contentType",
               "serializedName": "Content-Type",
               "type": {
-                "$ref": "11"
+                "$ref": "5"
               },
               "location": "Header",
               "isApiVersion": false,