diff --git a/python/packages/openai/agent_framework_openai/_chat_client.py b/python/packages/openai/agent_framework_openai/_chat_client.py
index 9b394306bf9..c9f2e6de300 100644
--- a/python/packages/openai/agent_framework_openai/_chat_client.py
+++ b/python/packages/openai/agent_framework_openai/_chat_client.py
@@ -1441,10 +1441,10 @@ async def _prepare_options(
                             "type": "function",
                             "name": func_name,
                         }
-                    elif mode == "auto" and (allowed := tool_mode.get("allowed_tools")) is not None:
+                    elif mode in ("auto", "required") and (allowed := tool_mode.get("allowed_tools")) is not None:
                         run_options["tool_choice"] = {
                             "type": "allowed_tools",
-                            "mode": "auto",
+                            "mode": mode,
                             "tools": [{"type": "function", "name": name} for name in allowed],
                         }
                     else:
diff --git a/python/packages/openai/tests/openai/test_openai_chat_client.py b/python/packages/openai/tests/openai/test_openai_chat_client.py
index 964316f2712..7849f4b67dc 100644
--- a/python/packages/openai/tests/openai/test_openai_chat_client.py
+++ b/python/packages/openai/tests/openai/test_openai_chat_client.py
@@ -6183,6 +6183,90 @@ def get_weather(city: str) -> str:
     assert run_options["tool_choice"] == "auto"
 
 
+async def test_prepare_options_allowed_tools_required() -> None:
+    """Test that _prepare_options converts allowed_tools with required mode to OpenAI API format."""
+    client = OpenAIChatClient(model="test-model", api_key="test-key")
+
+    @tool
+    def get_weather(city: str) -> str:
+        """Get the weather for a city."""
+        return f"Sunny in {city}"
+
+    @tool
+    def search_docs(query: str) -> str:
+        """Search documentation."""
+        return f"Results for {query}"
+
+    messages = [Message(role="user", contents=[Content.from_text(text="Hello")])]
+    options: dict[str, Any] = {
+        "model": "test-model",
+        "tools": [get_weather, search_docs],
+        "tool_choice": {"mode": "required", "allowed_tools": ["search_docs"]},
+    }
+
+    run_options = await client._prepare_options(messages, options)
+
+    assert run_options["tool_choice"] == {
+        "type": "allowed_tools",
+        "mode": "required",
+        "tools": [{"type": "function", "name": "search_docs"}],
+    }
+
+
+async def test_prepare_options_allowed_tools_required_multiple() -> None:
+    """Test that _prepare_options converts multiple allowed_tools with required mode correctly."""
+    client = OpenAIChatClient(model="test-model", api_key="test-key")
+
+    @tool
+    def get_weather(city: str) -> str:
+        """Get the weather for a city."""
+        return f"Sunny in {city}"
+
+    @tool
+    def search_docs(query: str) -> str:
+        """Search documentation."""
+        return f"Results for {query}"
+
+    messages = [Message(role="user", contents=[Content.from_text(text="Hello")])]
+    options: dict[str, Any] = {
+        "model": "test-model",
+        "tools": [get_weather, search_docs],
+        "tool_choice": {"mode": "required", "allowed_tools": ["get_weather", "search_docs"]},
+    }
+
+    run_options = await client._prepare_options(messages, options)
+
+    assert run_options["tool_choice"] == {
+        "type": "allowed_tools",
+        "mode": "required",
+        "tools": [
+            {"type": "function", "name": "get_weather"},
+            {"type": "function", "name": "search_docs"},
+        ],
+    }
+
+
+async def test_prepare_options_required_without_allowed_tools() -> None:
+    """Test that required mode without allowed_tools still returns plain 'required' string."""
+    client = OpenAIChatClient(model="test-model", api_key="test-key")
+
+    @tool
+    def get_weather(city: str) -> str:
+        """Get the weather for a city."""
+        return f"Sunny in {city}"
+
+    messages = [Message(role="user", contents=[Content.from_text(text="Hello")])]
+    options: dict[str, Any] = {
+        "model": "test-model",
+        "tools": [get_weather],
+        "tool_choice": {"mode": "required"},
+    }
+
+    run_options = await client._prepare_options(messages, options)
+
+    assert run_options["tool_choice"] == "required"
+
+
 # endregion