diff --git a/openhands/llm/llm.py b/openhands/llm/llm.py
index f97669309c..b94ed3bc2b 100644
--- a/openhands/llm/llm.py
+++ b/openhands/llm/llm.py
@@ -188,13 +188,13 @@ class LLM(RetryMixin, DebugMixin):
         if 'claude-opus-4-1' in self.config.model.lower():
             kwargs['thinking'] = {'type': 'disabled'}
 
-        # Anthropic constraint: Opus models cannot accept both temperature and top_p
+        # Anthropic constraint: Opus 4.1 and Sonnet 4 models cannot accept both temperature and top_p
         # Prefer temperature (drop top_p) if both are specified.
         _model_lower = self.config.model.lower()
-        # Limit to Opus 4.1 specifically to avoid changing behavior of other Anthropic models
-        if ('claude-opus-4-1' in _model_lower) and (
-            'temperature' in kwargs and 'top_p' in kwargs
-        ):
+        # Apply to Opus 4.1 and Sonnet 4 models to avoid API errors
+        if (
+            ('claude-opus-4-1' in _model_lower) or ('claude-sonnet-4' in _model_lower)
+        ) and ('temperature' in kwargs and 'top_p' in kwargs):
             kwargs.pop('top_p', None)
 
         # Add completion_kwargs if present
diff --git a/tests/unit/llm/test_llm.py b/tests/unit/llm/test_llm.py
index a6fc7c6726..dfdb4e05b4 100644
--- a/tests/unit/llm/test_llm.py
+++ b/tests/unit/llm/test_llm.py
@@ -1255,6 +1255,25 @@ def test_opus_41_keeps_temperature_top_p(mock_completion):
     assert 'top_p' not in call_kwargs
 
 
+@patch('openhands.llm.llm.litellm_completion')
+def test_sonnet_4_keeps_temperature_drops_top_p(mock_completion):
+    mock_completion.return_value = {
+        'choices': [{'message': {'content': 'ok'}}],
+    }
+    config = LLMConfig(
+        model='anthropic/claude-sonnet-4-20250514',
+        api_key='k',
+        temperature=0.7,
+        top_p=0.9,
+    )
+    llm = LLM(config, service_id='svc')
+    llm.completion(messages=[{'role': 'user', 'content': 'hi'}])
+    call_kwargs = mock_completion.call_args[1]
+    assert call_kwargs.get('temperature') == 0.7
+    # Anthropic rejects both temperature and top_p together on Sonnet 4; we keep temperature and drop top_p
+    assert 'top_p' not in call_kwargs
+
+
 @patch('openhands.llm.llm.litellm_completion')
 def test_opus_4_keeps_temperature_top_p(mock_completion):
     mock_completion.return_value = {