diff --git a/litellm/completion_extras/litellm_responses_transformation/transformation.py b/litellm/completion_extras/litellm_responses_transformation/transformation.py
index 5a6debc4af5..a76032854b7 100644
--- a/litellm/completion_extras/litellm_responses_transformation/transformation.py
+++ b/litellm/completion_extras/litellm_responses_transformation/transformation.py
@@ -502,7 +502,11 @@ class LiteLLMResponsesTransformationHandler(CompletionTransformationBridge):
             elif key == "response_format":
                 text_format = self._transform_response_format_to_text_format(value)
                 if text_format:
-                    responses_api_request["text"] = text_format
+                    existing_text = cast("dict[str, object]", responses_api_request["text"] if "text" in responses_api_request else {})
+                    responses_api_request["text"] = cast("ResponseText", {**existing_text, **text_format})
+            elif key == "verbosity":
+                existing_text = cast("dict[str, object]", responses_api_request["text"] if "text" in responses_api_request else {})
+                responses_api_request["text"] = cast("ResponseText", {**existing_text, "verbosity": value})
             elif key == "tool_choice":
                 responses_api_request["tool_choice"] = self._normalize_tool_choice_for_responses_api(value)
             elif key == "stream_options":
diff --git a/tests/test_litellm/completion_extras/litellm_responses_transformation/test_completion_extras_litellm_responses_transformation_transformation.py b/tests/test_litellm/completion_extras/litellm_responses_transformation/test_completion_extras_litellm_responses_transformation_transformation.py
index e4ada0a9b31..c326ad4a0f7 100644
--- a/tests/test_litellm/completion_extras/litellm_responses_transformation/test_completion_extras_litellm_responses_transformation_transformation.py
+++ b/tests/test_litellm/completion_extras/litellm_responses_transformation/test_completion_extras_litellm_responses_transformation_transformation.py
@@ -4287,3 +4287,36 @@ def test_system_string_after_a_developer_message_stays_in_input_in_client_order(
     assert instructions is None
     assert [item["role"] for item in input_items] == ["developer", "system", "user"]
     assert input_items[1] == _system_input_item("Be brief.")
+
+
+def test_map_optional_params_verbosity_merges_into_text():
+    """Chat verbosity must land on Responses text.verbosity alongside text.format regardless of key order."""
+    from litellm.completion_extras.litellm_responses_transformation.transformation import (
+        LiteLLMResponsesTransformationHandler,
+    )
+    from litellm.types.llms.openai import ResponsesAPIOptionalRequestParams
+
+    handler: Final = LiteLLMResponsesTransformationHandler()
+
+    responses_api_request = ResponsesAPIOptionalRequestParams()
+    handler._map_optional_params_to_responses_api_request(
+        {"verbosity": "low", "response_format": {"type": "json_object"}},
+        responses_api_request,
+    )
+    assert responses_api_request["text"]["verbosity"] == "low"
+    assert responses_api_request["text"]["format"]["type"] == "json_object"
+
+    reversed_request = ResponsesAPIOptionalRequestParams()
+    handler._map_optional_params_to_responses_api_request(
+        {"response_format": {"type": "json_object"}, "verbosity": "low"},
+        reversed_request,
+    )
+    assert reversed_request["text"]["verbosity"] == "low"
+    assert reversed_request["text"]["format"]["type"] == "json_object"
+
+    verbosity_only_request = ResponsesAPIOptionalRequestParams()
+    handler._map_optional_params_to_responses_api_request(
+        {"verbosity": "low"},
+        verbosity_only_request,
+    )
+    assert verbosity_only_request["text"] == {"verbosity": "low"}