diff --git a/src/Libraries/Microsoft.Extensions.AI/Image/ImageGeneratorBuilderServiceCollectionExtensions.cs b/src/Libraries/Microsoft.Extensions.AI/Image/ImageGeneratorBuilderServiceCollectionExtensions.cs
index ec19252a319..7868adf2eb3 100644
--- a/src/Libraries/Microsoft.Extensions.AI/Image/ImageGeneratorBuilderServiceCollectionExtensions.cs
+++ b/src/Libraries/Microsoft.Extensions.AI/Image/ImageGeneratorBuilderServiceCollectionExtensions.cs
@@ -55,7 +55,7 @@ public static ImageGeneratorBuilder AddImageGenerator(
     /// <remarks>The generator is registered as a scoped service.</remarks>
     public static ImageGeneratorBuilder AddKeyedImageGenerator(
         this IServiceCollection serviceCollection,
-        object serviceKey,
+        object? serviceKey,
         IImageGenerator innerGenerator,
         ServiceLifetime lifetime = ServiceLifetime.Singleton)
         => AddKeyedImageGenerator(serviceCollection, serviceKey, _ => innerGenerator, lifetime);
@@ -70,12 +70,11 @@ public static ImageGeneratorBuilder AddKeyedImageGenerator(
     /// <remarks>The generator is registered as a scoped service.</remarks>
     public static ImageGeneratorBuilder AddKeyedImageGenerator(
         this IServiceCollection serviceCollection,
-        object serviceKey,
+        object? serviceKey,
         Func<IServiceProvider, IImageGenerator> innerGeneratorFactory,
         ServiceLifetime lifetime = ServiceLifetime.Singleton)
     {
         _ = Throw.IfNull(serviceCollection);
-        _ = Throw.IfNull(serviceKey);
         _ = Throw.IfNull(innerGeneratorFactory);
 
         var builder = new ImageGeneratorBuilder(innerGeneratorFactory);
diff --git a/src/Libraries/Microsoft.Extensions.AI/SpeechToText/SpeechToTextClientBuilderServiceCollectionExtensions.cs b/src/Libraries/Microsoft.Extensions.AI/SpeechToText/SpeechToTextClientBuilderServiceCollectionExtensions.cs
index 5ef54e8db26..243cb057068 100644
--- a/src/Libraries/Microsoft.Extensions.AI/SpeechToText/SpeechToTextClientBuilderServiceCollectionExtensions.cs
+++ b/src/Libraries/Microsoft.Extensions.AI/SpeechToText/SpeechToTextClientBuilderServiceCollectionExtensions.cs
@@ -52,7 +52,7 @@ public static SpeechToTextClientBuilder AddSpeechToTextClient(
     /// <remarks>The client is registered as a scoped service.</remarks>
     public static SpeechToTextClientBuilder AddKeyedSpeechToTextClient(
         this IServiceCollection serviceCollection,
-        object serviceKey,
+        object? serviceKey,
         ISpeechToTextClient innerClient,
         ServiceLifetime lifetime = ServiceLifetime.Singleton)
         => AddKeyedSpeechToTextClient(serviceCollection, serviceKey, _ => innerClient, lifetime);
@@ -66,12 +66,11 @@ public static SpeechToTextClientBuilder AddKeyedSpeechToTextClient(
     /// <remarks>The client is registered as a scoped service.</remarks>
     public static SpeechToTextClientBuilder AddKeyedSpeechToTextClient(
         this IServiceCollection serviceCollection,
-        object serviceKey,
+        object? serviceKey,
         Func<IServiceProvider, ISpeechToTextClient> innerClientFactory,
         ServiceLifetime lifetime = ServiceLifetime.Singleton)
     {
         _ = Throw.IfNull(serviceCollection);
-        _ = Throw.IfNull(serviceKey);
         _ = Throw.IfNull(innerClientFactory);
 
         var builder = new SpeechToTextClientBuilder(innerClientFactory);
diff --git a/test/Libraries/Microsoft.Extensions.AI.Tests/Image/ImageGeneratorDependencyInjectionPatterns.cs b/test/Libraries/Microsoft.Extensions.AI.Tests/Image/ImageGeneratorDependencyInjectionPatterns.cs
index b65495e506b..a17cd5a5c41 100644
--- a/test/Libraries/Microsoft.Extensions.AI.Tests/Image/ImageGeneratorDependencyInjectionPatterns.cs
+++ b/test/Libraries/Microsoft.Extensions.AI.Tests/Image/ImageGeneratorDependencyInjectionPatterns.cs
@@ -154,6 +154,22 @@ public void AddKeyedImageGenerator_RegistersExpectedLifetime(ServiceLifetime? li
         Assert.Equal(expectedLifetime, sd.Lifetime);
     }
 
+    [Fact]
+    public void AddKeyedImageGenerator_WorksWithNullServiceKey()
+    {
+        ServiceCollection sc = new();
+        sc.AddKeyedImageGenerator(null, _ => new TestImageGenerator());
+
+        ServiceDescriptor sd = Assert.Single(sc);
+        Assert.Equal(typeof(IImageGenerator), sd.ServiceType);
+        Assert.False(sd.IsKeyedService);
+        Assert.Null(sd.ServiceKey);
+        Assert.Null(sd.ImplementationInstance);
+        Assert.NotNull(sd.ImplementationFactory);
+        Assert.IsType<TestImageGenerator>(sd.ImplementationFactory(null!));
+        Assert.Equal(ServiceLifetime.Singleton, sd.Lifetime);
+    }
+
     public class SingletonMiddleware(IImageGenerator inner, IServiceProvider services) : DelegatingImageGenerator(inner)
     {
         public new IImageGenerator InnerGenerator => base.InnerGenerator;
diff --git a/test/Libraries/Microsoft.Extensions.AI.Tests/SpeechToText/SpeechToTextClientDependencyInjectionPatterns.cs b/test/Libraries/Microsoft.Extensions.AI.Tests/SpeechToText/SpeechToTextClientDependencyInjectionPatterns.cs
index 07596a1bb6f..5595e1c82ce 100644
--- a/test/Libraries/Microsoft.Extensions.AI.Tests/SpeechToText/SpeechToTextClientDependencyInjectionPatterns.cs
+++ b/test/Libraries/Microsoft.Extensions.AI.Tests/SpeechToText/SpeechToTextClientDependencyInjectionPatterns.cs
@@ -154,6 +154,22 @@ public void AddKeyedSpeechToTextClient_RegistersExpectedLifetime(ServiceLifetime
         Assert.Equal(expectedLifetime, sd.Lifetime);
     }
 
+    [Fact]
+    public void AddKeyedSpeechToTextClient_WorksWithNullServiceKey()
+    {
+        ServiceCollection sc = new();
+        sc.AddKeyedSpeechToTextClient(null, _ => new TestSpeechToTextClient());
+
+        ServiceDescriptor sd = Assert.Single(sc);
+        Assert.Equal(typeof(ISpeechToTextClient), sd.ServiceType);
+        Assert.False(sd.IsKeyedService);
+        Assert.Null(sd.ServiceKey);
+        Assert.Null(sd.ImplementationInstance);
+        Assert.NotNull(sd.ImplementationFactory);
+        Assert.IsType<TestSpeechToTextClient>(sd.ImplementationFactory(null!));
+        Assert.Equal(ServiceLifetime.Singleton, sd.Lifetime);
+    }
+
     public class SingletonMiddleware(ISpeechToTextClient inner, IServiceProvider services) : DelegatingSpeechToTextClient(inner)
     {
         public new ISpeechToTextClient InnerClient => base.InnerClient;