diff --git a/test/Worker/Grpc.Tests/DependencyInjection/DurableTaskWorkerBuilderExtensionsAzureBlobPayloadsTests.cs b/test/Worker/Grpc.Tests/DependencyInjection/DurableTaskWorkerBuilderExtensionsAzureBlobPayloadsTests.cs
new file mode 100644
index 000000000..dd8202b33
--- /dev/null
+++ b/test/Worker/Grpc.Tests/DependencyInjection/DurableTaskWorkerBuilderExtensionsAzureBlobPayloadsTests.cs
@@ -0,0 +1,97 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Microsoft.DurableTask.Converters;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+using P = Microsoft.DurableTask.Protobuf;
+
+namespace Microsoft.DurableTask.Worker.Grpc.Tests;
+
+public class DurableTaskWorkerBuilderExtensionsAzureBlobPayloadsTests
+{
+    [Fact]
+    public void UseExternalizedPayloads_AddsLargePayloadsCapability()
+    {
+        // Arrange
+        ServiceCollection services = new();
+        DefaultDurableTaskWorkerBuilder builder = new("test", services);
+        
+        // Configure a minimal gRPC worker with channel
+        GrpcChannel channel = GetChannel();
+        builder.UseGrpc(opt => opt.Channel = channel);
+        
+        // Register a fake PayloadStore
+        services.AddSingleton<PayloadStore>(new FakePayloadStore());
+        
+        // Configure storage options
+        services.Configure<LargePayloadStorageOptions>("test", opts =>
+        {
+            opts.ContainerName = "test";
+            opts.ConnectionString = "UseDevelopmentStorage=true";
+        });
+
+        // Act
+        builder.UseExternalizedPayloads();
+
+        // Assert
+        IServiceProvider provider = services.BuildServiceProvider();
+        GrpcDurableTaskWorkerOptions options = provider.GetService<IOptionsMonitor<GrpcDurableTaskWorkerOptions>>()!.Get("test");
+        
+        options.Capabilities.Should().Contain(P.WorkerCapability.LargePayloads);
+    }
+
+    [Fact]
+    public void UseExternalizedPayloads_WithConfigure_AddsLargePayloadsCapability()
+    {
+        // Arrange
+        ServiceCollection services = new();
+        DefaultDurableTaskWorkerBuilder builder = new("test", services);
+        
+        // Configure a minimal gRPC worker with channel
+        GrpcChannel channel = GetChannel();
+        builder.UseGrpc(opt => opt.Channel = channel);
+        
+        // Register a fake PayloadStore
+        services.AddSingleton<PayloadStore>(new FakePayloadStore());
+
+        // Act
+        builder.UseExternalizedPayloads(opts =>
+        {
+            opts.ContainerName = "test";
+            opts.ConnectionString = "UseDevelopmentStorage=true";
+        });
+
+        // Assert
+        IServiceProvider provider = services.BuildServiceProvider();
+        GrpcDurableTaskWorkerOptions options = provider.GetService<IOptionsMonitor<GrpcDurableTaskWorkerOptions>>()!.Get("test");
+        
+        options.Capabilities.Should().Contain(P.WorkerCapability.LargePayloads);
+    }
+
+#if NET6_0_OR_GREATER
+    static GrpcChannel GetChannel() => GrpcChannel.ForAddress("http://localhost:9001");
+#endif
+
+#if NETFRAMEWORK
+    static GrpcChannel GetChannel() => new("http://localhost:9001", ChannelCredentials.Insecure);
+#endif
+
+    class FakePayloadStore : PayloadStore
+    {
+        public override Task<string> DownloadAsync(string token, CancellationToken cancellationToken)
+        {
+            return Task.FromResult("fake");
+        }
+
+        public override bool IsKnownPayloadToken(string value)
+        {
+            return value.StartsWith("fake:");
+        }
+
+        public override Task<string> UploadAsync(string payLoad, CancellationToken cancellationToken)
+        {
+            return Task.FromResult("fake:token");
+        }
+    }
+}
diff --git a/test/Worker/Grpc.Tests/Worker.Grpc.Tests.csproj b/test/Worker/Grpc.Tests/Worker.Grpc.Tests.csproj
index cda2aa55a..3389656c3 100644
--- a/test/Worker/Grpc.Tests/Worker.Grpc.Tests.csproj
+++ b/test/Worker/Grpc.Tests/Worker.Grpc.Tests.csproj
@@ -10,6 +10,7 @@
 
   <ItemGroup>
     <ProjectReference Include="$(SrcRoot)Worker/Grpc/Worker.Grpc.csproj" />
+    <ProjectReference Include="$(SrcRoot)Extensions/AzureBlobPayloads/AzureBlobPayloads.csproj" />
   </ItemGroup>
 
 </Project>