diff --git a/litellm/integrations/langfuse/langfuse_otel.py b/litellm/integrations/langfuse/langfuse_otel.py
index ee75e6501e8..6f6becf44e7 100644
--- a/litellm/integrations/langfuse/langfuse_otel.py
+++ b/litellm/integrations/langfuse/langfuse_otel.py
@@ -688,6 +688,7 @@ def _output_items(item: object) -> tuple[dict[str, object], ...]:
                 "call_id": _attr(item, "call_id", ""),
                 "type": "function_call",
                 "arguments": safe_json_loads(arguments, default={}) if isinstance(arguments, str) else arguments,
+                **({"namespace": namespace} if (namespace := _attr(item, "namespace")) is not None else {}),
             },
         )
     return ()
diff --git a/tests/unit/integrations/test_langfuse_otel.py b/tests/unit/integrations/test_langfuse_otel.py
index a2803719c75..9dbca18f47b 100644
--- a/tests/unit/integrations/test_langfuse_otel.py
+++ b/tests/unit/integrations/test_langfuse_otel.py
@@ -976,7 +976,8 @@ class TestLangfuseOtelResponsesAPI:
             assert len(trace_output_calls) > 0, "trace.output should be set"
             assert trace_output_calls[0].args[2] == output_json
 
-    def test_responses_api_with_function_calls(self):
+    @pytest.mark.parametrize("namespace", (None, "weather", ""))
+    def test_responses_api_with_function_calls(self, namespace: str | None):
         """Test Langfuse OTEL logger with Responses API function_call output."""
         from litellm.types.integrations.langfuse_otel import LangfuseSpanAttributes
         from openai.types.responses import ResponseFunctionToolCall
@@ -990,6 +991,7 @@ class TestLangfuseOtelResponsesAPI:
                     id="fc-123",
                     type="function_call",
                     name="get_weather",
+                    namespace=namespace,
                     call_id="call-abc",
                     arguments='{"location": "San Francisco", "unit": "celsius"}',
                     status="completed",
@@ -1037,6 +1039,10 @@ class TestLangfuseOtelResponsesAPI:
             assert output_data[0]["call_id"] == "call-abc"
             assert output_data[0]["arguments"]["location"] == "San Francisco"
             assert output_data[0]["arguments"]["unit"] == "celsius"
+            if namespace is None:
+                assert "namespace" not in output_data[0]
+            else:
+                assert output_data[0]["namespace"] == namespace
 
     def test_responses_api_function_call_with_redacted_arguments(self):
         """Sentinel arguments (invalid JSON) must not kill the whole observation output."""