diff --git a/litellm/llms/bedrock/chat/converse_transformation.py b/litellm/llms/bedrock/chat/converse_transformation.py
index 38dabafa441..b995a948dd8 100644
--- a/litellm/llms/bedrock/chat/converse_transformation.py
+++ b/litellm/llms/bedrock/chat/converse_transformation.py
@@ -426,8 +426,6 @@ class AmazonConverseConfig(BaseConfig):
         if "gpt-oss" in model:
             optional_params["reasoning_effort"] = reasoning_effort
         elif "openai.gpt-5" in model:
-            # Converse rejects Anthropic's `thinking` for OpenAI GPT-5.x; effort goes
-            # under additionalModelRequestFields as {"reasoning": {"effort": ...}}.
             optional_params.pop("thinking", None)
             optional_params["reasoning"] = {"effort": reasoning_effort}
         elif self._is_nova_2_model(model):
@@ -561,7 +559,7 @@ class AmazonConverseConfig(BaseConfig):
             # only anthropic and mistral support tool choice config. otherwise (E.g. cohere) will fail the call - https://docs.aws.amazon.com/bedrock/latest/APIReference/API_runtime_ToolChoice.html
             supported_params.append("tool_choice")
 
-        if "gpt-oss" in model:
+        if "gpt-oss" in model or "openai.gpt-5" in model or "openai.gpt-5" in base_model:
             supported_params.append("reasoning_effort")
         elif self._is_nova_2_model(model):
             # Nova 2 models support reasoning_effort (transformed to reasoningConfig)
@@ -909,7 +907,7 @@ class AmazonConverseConfig(BaseConfig):
                 optional_params["_parallel_tool_use_config"] = {
                     "tool_choice": {"type": "auto", "disable_parallel_tool_use": not value}
                 }
-            if param == "thinking":
+            if param == "thinking" and "openai.gpt-5" not in model:
                 if (
                     isinstance(value, dict)
                     and value.get("type") == "adaptive"
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 66b588168e9..c5ab6027f45 100644
--- a/tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py
+++ b/tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py
@@ -315,6 +315,40 @@ def test_reasoning_effort_maps_to_reasoning_effort_for_openai_gpt5_converse(mode
     assert "thinking" not in additional_request_params
 
 
+@pytest.mark.parametrize(
+    "model",
+    [
+        "us.openai.gpt-5.6-sol",
+        "bedrock/converse/global.openai.gpt-5.6-luna",
+    ],
+)
+def test_openai_gpt5_converse_never_forwards_thinking(model, local_model_cost_map):
+    """GPT-5.x on Converse must never send Anthropic ``thinking``/``output_config`` (Bedrock rejects them).
+
+    Regression: ``thinking`` is not advertised as supported, and even when supplied alongside
+    ``reasoning_effort`` in either order it never survives into the request."""
+    config = AmazonConverseConfig()
+
+    supported = config.get_supported_openai_params(model=model)
+    assert "thinking" not in supported
+    assert "output_config" not in supported
+
+    thinking_block = {"type": "enabled", "budget_tokens": 2048}
+    for non_default_params in (
+        {"reasoning_effort": "high", "thinking": thinking_block},
+        {"thinking": thinking_block, "reasoning_effort": "high"},
+    ):
+        optional_params = config.map_openai_params(
+            non_default_params=dict(non_default_params),
+            optional_params={},
+            model=model,
+            drop_params=False,
+        )
+        _, additional_request_params, _, _ = config._prepare_request_params(optional_params, model)
+        assert additional_request_params["reasoning"] == {"effort": "high"}
+        assert "thinking" not in additional_request_params
+
+
 @pytest.mark.parametrize(
     "model",
     [