diff --git a/src/Http/Http.Extensions/src/DefaultProblemDetailsWriter.cs b/src/Http/Http.Extensions/src/DefaultProblemDetailsWriter.cs
index 4d47a1e54f06..b02d719b9086 100644
--- a/src/Http/Http.Extensions/src/DefaultProblemDetailsWriter.cs
+++ b/src/Http/Http.Extensions/src/DefaultProblemDetailsWriter.cs
@@ -56,7 +56,8 @@ public ValueTask WriteAsync(ProblemDetailsContext context)
         ProblemDetailsDefaults.Apply(context.ProblemDetails, httpContext.Response.StatusCode);
 
         var traceId = Activity.Current?.Id ?? httpContext.TraceIdentifier;
-        context.ProblemDetails.Extensions["traceId"] = traceId;
+        var traceIdKeyName = _serializerOptions.PropertyNamingPolicy?.ConvertName("traceId") ?? "traceId";
+        context.ProblemDetails.Extensions[traceIdKeyName] = traceId;
 
         _options.CustomizeProblemDetails?.Invoke(context);
 
diff --git a/src/Http/Http.Extensions/test/ProblemDetailsDefaultWriterTest.cs b/src/Http/Http.Extensions/test/ProblemDetailsDefaultWriterTest.cs
index d57a440a4593..2afabbec3f06 100644
--- a/src/Http/Http.Extensions/test/ProblemDetailsDefaultWriterTest.cs
+++ b/src/Http/Http.Extensions/test/ProblemDetailsDefaultWriterTest.cs
@@ -85,7 +85,7 @@ public async Task WriteAsync_Works_ProperCasing()
         //Assert
         stream.Position = 0;
         var result = await JsonSerializer.DeserializeAsync<Dictionary<string, object>>(stream, JsonSerializerOptions.Default);
-        Assert.Equal(result.Keys, new(new() { { "type", 0 }, { "title", 1 }, { "status", 2 }, { "detail", 3 }, { "instance", 4 }, { "extensionKey", 5 }, {"traceId", expectedTraceId } }));
+        Assert.Equal(result.Keys, new(new() { { "type", 0 }, { "title", 1 }, { "status", 2 }, { "detail", 3 }, { "instance", 4 }, { "extensionKey", 5 }, { "traceId", expectedTraceId } }));
     }
 
     [Fact]
@@ -117,7 +117,7 @@ public async Task WriteAsync_Works_ProperCasing_ValidationProblemDetails()
         //Assert
         stream.Position = 0;
         var result = await JsonSerializer.DeserializeAsync<Dictionary<string, object>>(stream, JsonSerializerOptions.Default);
-        Assert.Equal(result.Keys, new(new() { { "type", 0 }, { "title", 1 }, { "status", 2 }, { "detail", 3 }, { "instance", 4 }, { "errors", 5 }, {"traceId", expectedTraceId } }));
+        Assert.Equal(result.Keys, new(new() { { "type", 0 }, { "title", 1 }, { "status", 2 }, { "detail", 3 }, { "instance", 4 }, { "errors", 5 }, { "traceId", expectedTraceId } }));
     }
 
     [Fact]
@@ -689,6 +689,57 @@ private static HttpContext CreateContext(
         return context;
     }
 
+    [Theory]
+    [InlineData("SnakeCaseLower", "trace_id")]
+    [InlineData("CamelCase", "traceId")]
+    [InlineData("KebabCaseLower", "trace-id")]
+    [InlineData("KebabCaseUpper", "TRACE-ID")]
+    [InlineData("SnakeCaseUpper", "TRACE_ID")]
+    public async Task TestPropertyNamingPolicyChanges(string caseSelection, string extensionVariableName)
+    {
+        // Arrange
+        JsonNamingPolicy propertyNamingPolicy = caseSelection switch
+        {
+            "CamelCase" => JsonNamingPolicy.CamelCase,
+            "KebabCaseLower" => JsonNamingPolicy.KebabCaseLower,
+            "KebabCaseUpper" => JsonNamingPolicy.KebabCaseUpper,
+            "SnakeCaseLower" => JsonNamingPolicy.SnakeCaseLower,
+            "SnakeCaseUpper" => JsonNamingPolicy.SnakeCaseUpper,
+            _ => JsonNamingPolicy.KebabCaseLower
+        };
+
+        var options = new JsonOptions();
+        options.SerializerOptions.PropertyNamingPolicy = propertyNamingPolicy;
+
+        var writer = GetWriter(jsonOptions: options);
+        var stream = new MemoryStream();
+        var context = CreateContext(stream);
+
+        var expectedTraceId = Activity.Current?.Id ?? context.TraceIdentifier;
+        var expectedProblem = new ProblemDetails()
+        {
+            Detail = "Custom Bad Request",
+            Instance = "Custom Bad Request",
+            Status = StatusCodes.Status400BadRequest,
+            Type = "https://tools.ietf.org/html/rfc9110#section-15.5.1-custom",
+            Title = "Custom Bad Request",
+        };
+        var problemDetailsContext = new ProblemDetailsContext()
+        {
+            HttpContext = context,
+            ProblemDetails = expectedProblem
+        };
+
+        //Act
+        await writer.WriteAsync(problemDetailsContext);
+        stream.Position = 0;
+        using var reader = new StreamReader(stream);
+        var json = await reader.ReadToEndAsync();
+
+        //Assert
+        Assert.Contains($"\"{extensionVariableName}\":\"{expectedTraceId}\"", json);
+    }
+
     private static IServiceProvider CreateServices()
     {
         var services = new ServiceCollection();