diff --git a/litellm/llms/bedrock/chat/converse_transformation.py b/litellm/llms/bedrock/chat/converse_transformation.py
index 08f44d5b1b1..d7ee15cedd7 100644
--- a/litellm/llms/bedrock/chat/converse_transformation.py
+++ b/litellm/llms/bedrock/chat/converse_transformation.py
@@ -857,6 +857,9 @@ class AmazonConverseConfig(BaseConfig):
         drop_params: bool,
     ) -> dict:
         is_thinking_enabled = self.is_thinking_enabled(non_default_params)
+        accepts_thinking_param = self._model_accepts_anthropic_thinking_param(
+            model=model, base_model=BedrockModelInfo.get_base_model(model)
+        )
 
         for param, value in non_default_params.items():
             if param == "response_format" and isinstance(value, dict):
@@ -906,7 +909,12 @@ class AmazonConverseConfig(BaseConfig):
                 optional_params["_parallel_tool_use_config"] = {
                     "tool_choice": {"disable_parallel_tool_use": disable_parallel}
                 }
-            if param == "thinking":
+            if param == "thinking" and not accepts_thinking_param:
+                verbose_logger.debug(
+                    "Dropping unsupported `thinking` param for Bedrock model=%s; it reasons natively and rejects it.",
+                    model,
+                )
+            elif param == "thinking":
                 if (
                     isinstance(value, dict)
                     and value.get("type") == "adaptive"
@@ -929,6 +937,11 @@ class AmazonConverseConfig(BaseConfig):
                         litellm.verbose_logger.warning(DROP_UNSUPPORTED_ADAPTIVE_THINKING_WARNING, model)
                 else:
                     optional_params["thinking"] = value
+            elif param == "reasoning_effort" and isinstance(value, str) and not accepts_thinking_param:
+                verbose_logger.debug(
+                    "Dropping unsupported `reasoning_effort` param for Bedrock model=%s; it reasons natively and rejects it.",
+                    model,
+                )
             elif param == "reasoning_effort" and isinstance(value, str):
                 self._handle_reasoning_effort_parameter(
                     model=model, reasoning_effort=value, optional_params=optional_params
diff --git a/tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py b/tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py
index f7e2716bd19..93455f00143 100644
--- a/tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py
+++ b/tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py
@@ -605,6 +605,34 @@ def test_bedrock_deepseek_r1_thinking_dropped_does_not_leak_into_request():
     assert "thinking" not in request.get("additionalModelRequestFields", {})
 
 
+@pytest.mark.parametrize("param", ["thinking", "reasoning_effort"])
+def test_bedrock_deepseek_r1_reasoning_params_not_forwarded_by_map(param):
+    """Even when map_openai_params is called directly (bypassing the supported-params
+    gate), DeepSeek R1 must not forward the Anthropic-shaped thinking/reasoning_effort
+    into additionalModelRequestFields, since Bedrock rejects it with a 400."""
+    config = AmazonConverseConfig()
+    model = "bedrock/converse/us.deepseek.r1-v1:0"
+    value = {"type": "enabled", "budget_tokens": 1024} if param == "thinking" else "high"
+
+    optional_params = config.map_openai_params(
+        non_default_params={param: value, "max_tokens": 100},
+        optional_params={},
+        model=model,
+        drop_params=False,
+    )
+    assert "thinking" not in optional_params
+    assert "reasoning_effort" not in optional_params
+
+    request = config._transform_request(
+        model=model,
+        messages=[{"role": "user", "content": "Say hi in one word."}],
+        optional_params=optional_params,
+        litellm_params={},
+        headers={},
+    )
+    assert request.get("additionalModelRequestFields") is None
+
+
 def test_get_supported_openai_params_bedrock_converse():
     """
     Test that all documented bedrock converse models have the same set of supported openai params when using