diff --git a/litellm/llms/gemini/realtime/transformation.py b/litellm/llms/gemini/realtime/transformation.py
index 327eee5fd94..2a8f4457e9c 100644
--- a/litellm/llms/gemini/realtime/transformation.py
+++ b/litellm/llms/gemini/realtime/transformation.py
@@ -417,9 +417,11 @@ class GeminiRealtimeConfig(BaseRealtimeConfig):
             else {"result": parsed_output}
         )
 
-        # Look up the function name from stored mapping and remove the
-        # entry to prevent unbounded growth in long-running sessions.
-        function_name = self._tool_call_id_to_name.pop(call_id, None)
+        # Look up the function name from stored mapping. Keep the entry so a
+        # client SDK that retries function_call_output (or sends it twice for
+        # the same tool call) still produces a Gemini toolResponse with the
+        # required ``name`` field.
+        function_name = self._tool_call_id_to_name.get(call_id)
         if not function_name:
             verbose_logger.warning(
                 f"Gemini Realtime: Function name not found for call_id={call_id}. "
diff --git a/tests/test_litellm/llms/gemini/realtime/test_gemini_realtime_transformation.py b/tests/test_litellm/llms/gemini/realtime/test_gemini_realtime_transformation.py
index 3d4b95d7740..f1dae60379a 100644
--- a/tests/test_litellm/llms/gemini/realtime/test_gemini_realtime_transformation.py
+++ b/tests/test_litellm/llms/gemini/realtime/test_gemini_realtime_transformation.py
@@ -534,6 +534,20 @@ def test_gemini_realtime_function_call_output_transformation():
     assert func_response["response"]["temperature"] == 72
     assert func_response["response"]["conditions"] == "sunny"
 
+    # A retry of the same function_call_output (e.g. a client SDK that
+    # re-sends the result) must still produce a functionResponses payload
+    # carrying ``name`` — the call_id → name mapping must not be evicted
+    # after the first lookup.
+    retry_messages = config.transform_realtime_request(
+        json.dumps(function_output),
+        "gemini-2.5-flash",
+        session_configuration_request="existing",
+    )
+    retry_response = json.loads(retry_messages[0])["toolResponse"]["functionResponses"][
+        0
+    ]
+    assert retry_response["name"] == "get_weather"
+
 
 def test_gemini_realtime_user_text_transformation():
     """Test transformation of OpenAI user message to Gemini clientContent format."""