diff --git a/src/llama_stack/providers/utils/inference/model_registry.py b/src/llama_stack/providers/utils/inference/model_registry.py
index d60d00f87..8a120b698 100644
--- a/src/llama_stack/providers/utils/inference/model_registry.py
+++ b/src/llama_stack/providers/utils/inference/model_registry.py
@@ -20,7 +20,7 @@ logger = get_logger(name=__name__, category="providers::utils")
 
 
 class RemoteInferenceProviderConfig(BaseModel):
-    allowed_models: list[str] | None = Field(  # TODO: make this non-optional and give a list() default
+    allowed_models: list[str] | None = Field(
         default=None,
         description="List of models that should be registered with the model registry. If None, all models are allowed.",
     )
diff --git a/src/llama_stack/providers/utils/inference/openai_mixin.py b/src/llama_stack/providers/utils/inference/openai_mixin.py
index 941772b0f..09059da09 100644
--- a/src/llama_stack/providers/utils/inference/openai_mixin.py
+++ b/src/llama_stack/providers/utils/inference/openai_mixin.py
@@ -83,9 +83,6 @@ class OpenAIMixin(NeedsRequestProviderData, ABC, BaseModel):
     # This is set in list_models() and used in check_model_availability()
     _model_cache: dict[str, Model] = {}
 
-    # List of allowed models for this provider, if empty all models allowed
-    allowed_models: list[str] = []
-
     # Optional field name in provider data to look for API key, which takes precedence
     provider_data_api_key_field: str | None = None
 
@@ -441,7 +438,7 @@ class OpenAIMixin(NeedsRequestProviderData, ABC, BaseModel):
         for provider_model_id in provider_models_ids:
             if not isinstance(provider_model_id, str):
                 raise ValueError(f"Model ID {provider_model_id} from list_provider_model_ids() is not a string")
-            if self.allowed_models and provider_model_id not in self.allowed_models:
+            if self.config.allowed_models is not None and provider_model_id not in self.config.allowed_models:
                 logger.info(f"Skipping model {provider_model_id} as it is not in the allowed models list")
                 continue
             model = self.construct_model_from_identifier(provider_model_id)
diff --git a/tests/unit/providers/utils/inference/test_openai_mixin.py b/tests/unit/providers/utils/inference/test_openai_mixin.py
index d98c096aa..0b5ea078b 100644
--- a/tests/unit/providers/utils/inference/test_openai_mixin.py
+++ b/tests/unit/providers/utils/inference/test_openai_mixin.py
@@ -455,8 +455,8 @@ class TestOpenAIMixinAllowedModels:
     """Test cases for allowed_models filtering functionality"""
 
     async def test_list_models_with_allowed_models_filter(self, mixin, mock_client_with_models, mock_client_context):
-        """Test that list_models filters models based on allowed_models set"""
-        mixin.allowed_models = {"some-mock-model-id", "another-mock-model-id"}
+        """Test that list_models filters models based on allowed_models"""
+        mixin.config.allowed_models = ["some-mock-model-id", "another-mock-model-id"]
 
         with mock_client_context(mixin, mock_client_with_models):
             result = await mixin.list_models()
@@ -470,8 +470,18 @@ class TestOpenAIMixinAllowedModels:
             assert "final-mock-model-id" not in model_ids
 
     async def test_list_models_with_empty_allowed_models(self, mixin, mock_client_with_models, mock_client_context):
-        """Test that empty allowed_models set allows all models"""
-        assert len(mixin.allowed_models) == 0
+        """Test that empty allowed_models allows no models"""
+        mixin.config.allowed_models = []
+
+        with mock_client_context(mixin, mock_client_with_models):
+            result = await mixin.list_models()
+
+            assert result is not None
+            assert len(result) == 0  # No models should be included
+
+    async def test_list_models_with_omitted_allowed_models(self, mixin, mock_client_with_models, mock_client_context):
+        """Test that omitted allowed_models allows all models"""
+        assert mixin.config.allowed_models is None
 
         with mock_client_context(mixin, mock_client_with_models):
             result = await mixin.list_models()
@@ -488,7 +498,7 @@ class TestOpenAIMixinAllowedModels:
         self, mixin, mock_client_with_models, mock_client_context
     ):
         """Test that check_model_availability respects allowed_models"""
-        mixin.allowed_models = {"final-mock-model-id"}
+        mixin.config.allowed_models = ["final-mock-model-id"]
 
         with mock_client_context(mixin, mock_client_with_models):
             assert await mixin.check_model_availability("final-mock-model-id")
@@ -536,7 +546,7 @@ class TestOpenAIMixinModelRegistration:
 
     async def test_register_model_with_allowed_models_filter(self, mixin, mock_client_with_models, mock_client_context):
         """Test model registration with allowed_models filtering"""
-        mixin.allowed_models = {"some-mock-model-id"}
+        mixin.config.allowed_models = ["some-mock-model-id"]
 
         # Test with allowed model
         allowed_model = Model(
@@ -690,7 +700,7 @@ class TestOpenAIMixinCustomListProviderModelIds:
         mixin = CustomListProviderModelIdsImplementation(
             config=config, custom_model_ids=["model-1", "model-2", "model-3"]
         )
-        mixin.allowed_models = ["model-1"]
+        mixin.config.allowed_models = ["model-1"]
 
         result = await mixin.list_models()