diff --git a/litellm/llms/openrouter/responses/transformation.py b/litellm/llms/openrouter/responses/transformation.py
index 217a419ed22..bdf421b4f61 100644
--- a/litellm/llms/openrouter/responses/transformation.py
+++ b/litellm/llms/openrouter/responses/transformation.py
@@ -13,6 +13,7 @@ from typing import Optional
 import litellm
 from litellm.llms.openai.responses.transformation import OpenAIResponsesAPIConfig
 from litellm.secret_managers.main import get_secret_str
+from litellm.types.llms.openai import ResponseInputParam
 from litellm.types.router import GenericLiteLLMParams
 from litellm.types.utils import LlmProviders
 
@@ -72,6 +73,23 @@ class OpenRouterResponsesAPIConfig(OpenAIResponsesAPIConfig):
 
         return f"{api_base}/responses"
 
+    def transform_responses_api_request(
+        self,
+        model: str,
+        input: str | ResponseInputParam,
+        response_api_optional_request_params: dict,
+        litellm_params: GenericLiteLLMParams,
+        headers: dict,
+    ) -> dict:
+        response_api_optional_request_params["store"] = False
+        return super().transform_responses_api_request(
+            model=model,
+            input=input,
+            response_api_optional_request_params=response_api_optional_request_params,
+            litellm_params=litellm_params,
+            headers=headers,
+        )
+
     def supports_native_websocket(self) -> bool:
         """OpenRouter does not support native WebSocket for Responses API"""
         return False
diff --git a/tests/test_litellm/llms/openrouter/responses/test_openrouter_responses_transformation.py b/tests/test_litellm/llms/openrouter/responses/test_openrouter_responses_transformation.py
index 62c372a3d93..b9e7682f432 100644
--- a/tests/test_litellm/llms/openrouter/responses/test_openrouter_responses_transformation.py
+++ b/tests/test_litellm/llms/openrouter/responses/test_openrouter_responses_transformation.py
@@ -13,6 +13,7 @@ import litellm
 from litellm.llms.openrouter.responses.transformation import (
     OpenRouterResponsesAPIConfig,
 )
+from litellm.types.router import GenericLiteLLMParams
 from litellm.types.utils import LlmProviders
 from litellm.utils import ProviderConfigManager
 
@@ -63,7 +64,6 @@ class TestOpenRouterResponsesAPIConfig:
     def test_validate_environment_raises_without_key(self, monkeypatch):
         """validate_environment should raise when no API key is available."""
         config = OpenRouterResponsesAPIConfig()
-        from litellm.types.router import GenericLiteLLMParams
 
         # Clear any globally set API keys so the validation correctly raises
         monkeypatch.setattr(litellm, "api_key", None)
@@ -80,6 +80,36 @@ class TestOpenRouterResponsesAPIConfig:
         except ValueError as e:
             assert "OpenRouter API key is required" in str(e)
 
+    def test_transform_responses_api_request_forces_store_false_when_true(self):
+        """OpenRouter only accepts store=false for Responses API requests."""
+        config = OpenRouterResponsesAPIConfig()
+        request_params = {"store": True, "temperature": 0.2}
+
+        transformed = config.transform_responses_api_request(
+            model="openai/o4-mini",
+            input="hello",
+            response_api_optional_request_params=request_params,
+            litellm_params=GenericLiteLLMParams(),
+            headers={},
+        )
+
+        assert transformed["store"] is False
+        assert transformed["temperature"] == 0.2
+
+    def test_transform_responses_api_request_forces_store_false_when_omitted(self):
+        """Omitted store should be sent as false instead of null/true."""
+        config = OpenRouterResponsesAPIConfig()
+
+        transformed = config.transform_responses_api_request(
+            model="openai/o4-mini",
+            input="hello",
+            response_api_optional_request_params={},
+            litellm_params=GenericLiteLLMParams(),
+            headers={},
+        )
+
+        assert transformed["store"] is False
+
 
 class TestOpenRouterResponsesAPIRegistration:
     """Test that OpenRouter is properly registered as a native Responses API provider."""