diff --git a/model_prices_and_context_window.json b/model_prices_and_context_window.json
index 6786fc33595..161ff8af409 100644
--- a/model_prices_and_context_window.json
+++ b/model_prices_and_context_window.json
@@ -30212,7 +30212,7 @@
         "input_cost_per_token": 3e-06,
         "input_cost_per_token_above_200k_tokens": 6e-06,
         "litellm_provider": "vertex_ai-anthropic_models",
-        "max_input_tokens": 200000,
+        "max_input_tokens": 1000000,
         "max_output_tokens": 64000,
         "max_tokens": 64000,
         "mode": "chat",
@@ -36902,7 +36902,7 @@
         "input_cost_per_token": 3e-06,
         "input_cost_per_token_above_200k_tokens": 6e-06,
         "litellm_provider": "vertex_ai-anthropic_models",
-        "max_input_tokens": 200000,
+        "max_input_tokens": 1000000,
         "max_output_tokens": 64000,
         "max_tokens": 64000,
         "mode": "chat",
diff --git a/tests/test_litellm/test_claude_opus_4_6_config.py b/tests/test_litellm/test_claude_opus_4_6_config.py
index 7ee2ea33957..aae4539afa4 100644
--- a/tests/test_litellm/test_claude_opus_4_6_config.py
+++ b/tests/test_litellm/test_claude_opus_4_6_config.py
@@ -224,3 +224,22 @@ def test_opus_4_6_bedrock_converse_registration():
     assert "us.anthropic.claude-opus-4-6-v1" in litellm.bedrock_converse_models
     assert "eu.anthropic.claude-opus-4-6-v1" in litellm.bedrock_converse_models
     assert "au.anthropic.claude-opus-4-6-v1" in litellm.bedrock_converse_models
+
+
+def test_vertex_ai_sonnet_4_6_has_1m_context_window():
+    json_path = os.path.join(
+        os.path.dirname(__file__), "../../model_prices_and_context_window.json"
+    )
+    with open(json_path) as f:
+        model_data = json.load(f)
+
+    for model_name in [
+        "vertex_ai/claude-sonnet-4-6",
+        "vertex_ai/claude-sonnet-4-6@default",
+    ]:
+        assert model_name in model_data, f"Missing model entry: {model_name}"
+        info = model_data[model_name]
+        assert info["litellm_provider"] == "vertex_ai-anthropic_models"
+        assert info["max_input_tokens"] == 1000000
+        assert info["max_output_tokens"] == 64000
+        assert info["max_tokens"] == 64000