diff --git a/python/sglang/srt/entrypoints/openai/protocol.py b/python/sglang/srt/entrypoints/openai/protocol.py
index ed52f535c..3a53dff3e 100644
--- a/python/sglang/srt/entrypoints/openai/protocol.py
+++ b/python/sglang/srt/entrypoints/openai/protocol.py
@@ -460,6 +460,34 @@ class ChatCompletionRequest(BaseModel):
                 values["tool_choice"] = "auto"
         return values
 
+    @model_validator(mode="before")
+    @classmethod
+    def normalize_reasoning_inputs(cls, values: Dict):
+        r = values.get("reasoning")
+        if r is None:
+            return values
+
+        if isinstance(r, dict):
+            effort = r.get("effort") or r.get("reasoning_effort")
+            if effort in {"low", "medium", "high"}:
+                values["reasoning_effort"] = effort
+
+            enabled = (
+                r.get("enabled")
+                if r.get("enabled") is not None
+                else r.get("enable", False)
+            )
+            if isinstance(enabled, str):
+                enabled = enabled.strip().lower() in {"1", "true", "yes", "y", "on"}
+            if enabled:
+                ctk = values.get("chat_template_kwargs")
+                if not isinstance(ctk, dict):
+                    ctk = {}
+                ctk.setdefault("thinking", True)
+                values["chat_template_kwargs"] = ctk
+
+        return values
+
     @model_validator(mode="before")
     @classmethod
     def set_json_schema(cls, values):
diff --git a/test/srt/openai_server/basic/test_protocol.py b/test/srt/openai_server/basic/test_protocol.py
index 9066e5339..fcaa9770b 100644
--- a/test/srt/openai_server/basic/test_protocol.py
+++ b/test/srt/openai_server/basic/test_protocol.py
@@ -192,6 +192,20 @@ class TestChatCompletionRequest(unittest.TestCase):
         self.assertFalse(request.stream_reasoning)
         self.assertEqual(request.chat_template_kwargs, {"custom_param": "value"})
 
+    def test_chat_completion_reasoning_effort(self):
+        """Test chat completion with reasoning effort"""
+        messages = [{"role": "user", "content": "Hello"}]
+        request = ChatCompletionRequest(
+            model="test-model",
+            messages=messages,
+            reasoning={
+                "enabled": True,
+                "reasoning_effort": "high",
+            },
+        )
+        self.assertEqual(request.reasoning_effort, "high")
+        self.assertEqual(request.chat_template_kwargs, {"thinking": True})
+
     def test_chat_completion_json_format(self):
         """Test chat completion json format"""
         transcript = "Good morning! It's 7:00 AM, and I'm just waking up. Today is going to be a busy day, "