diff --git a/litellm/proxy/common_request_processing.py b/litellm/proxy/common_request_processing.py
index 7d2954fd2dd..9296e9635cd 100644
--- a/litellm/proxy/common_request_processing.py
+++ b/litellm/proxy/common_request_processing.py
@@ -920,9 +920,17 @@ class ProxyBaseLLMRequestProcessing:
         ### AUTO STREAM USAGE TRACKING ###
         # If always_include_stream_usage is enabled and this is a streaming request
         # automatically add stream_options={'include_usage': True} if not already set
+        # NOTE: Only apply to chat completions, NOT Responses API routes.
+        # Azure/OpenAI Responses API does not support stream_options (usage is
+        # included automatically in response.completed events).
+        _is_responses_api_route = route_type in {
+            "aresponses",
+            "_aresponses_websocket",
+        }
         if (
             general_settings.get("always_include_stream_usage", False) is True
             and self.data.get("stream", False) is True
+            and not _is_responses_api_route
         ):
             # Only set if stream_options is not already provided by the client
             if "stream_options" not in self.data:
diff --git a/tests/test_litellm/test_responses_api_stream_options.py b/tests/test_litellm/test_responses_api_stream_options.py
new file mode 100644
index 00000000000..5351fdfdf38
--- /dev/null
+++ b/tests/test_litellm/test_responses_api_stream_options.py
@@ -0,0 +1,75 @@
+"""
+Unit tests for fix #28553: stream_options should NOT be injected for Responses API routes.
+
+The proxy's `common_processing_pre_call_logic` injects `stream_options={'include_usage': True}`
+when `always_include_stream_usage` is enabled. This must NOT happen for Responses API routes
+(`aresponses`, `_aresponses_websocket`) because the Responses API does not support
+`stream_options` — usage is included automatically in response.completed events.
+"""
+
+import pytest
+
+
+def _apply_stream_options_logic(data: dict, general_settings: dict, route_type: str):
+    """Reproduces the stream_options injection logic from common_processing_pre_call_logic."""
+    _is_responses_api_route = route_type in {
+        "aresponses",
+        "_aresponses_websocket",
+    }
+    if (
+        general_settings.get("always_include_stream_usage", False) is True
+        and data.get("stream", False) is True
+        and not _is_responses_api_route
+    ):
+        if "stream_options" not in data:
+            data["stream_options"] = {"include_usage": True}
+        elif (
+            isinstance(data["stream_options"], dict)
+            and "include_usage" not in data["stream_options"]
+        ):
+            data["stream_options"]["include_usage"] = True
+
+
+class TestStreamOptionsNotInjectedForResponsesAPI:
+    """Verify stream_options is skipped for Responses API routes."""
+
+    @pytest.mark.parametrize("route_type", ["aresponses", "_aresponses_websocket"])
+    def test_stream_options_not_injected_for_responses_routes(self, route_type):
+        """stream_options must NOT be added when route is a Responses API route."""
+        data = {"stream": True, "model": "gpt-4"}
+        _apply_stream_options_logic(
+            data, {"always_include_stream_usage": True}, route_type
+        )
+        assert "stream_options" not in data
+
+    def test_stream_options_injected_for_chat_completions(self):
+        """stream_options SHOULD be added for acompletion route."""
+        data = {"stream": True, "model": "gpt-4"}
+        _apply_stream_options_logic(
+            data, {"always_include_stream_usage": True}, "acompletion"
+        )
+        assert data["stream_options"] == {"include_usage": True}
+
+    def test_stream_options_not_injected_when_disabled(self):
+        """stream_options should NOT be added when always_include_stream_usage is False."""
+        data = {"stream": True, "model": "gpt-4"}
+        _apply_stream_options_logic(
+            data, {"always_include_stream_usage": False}, "acompletion"
+        )
+        assert "stream_options" not in data
+
+    def test_existing_stream_options_not_overwritten(self):
+        """If client already set stream_options with include_usage, don't overwrite."""
+        data = {"stream": True, "model": "gpt-4", "stream_options": {"include_usage": False}}
+        _apply_stream_options_logic(
+            data, {"always_include_stream_usage": True}, "acompletion"
+        )
+        assert data["stream_options"] == {"include_usage": False}
+
+    def test_non_streaming_request_skipped(self):
+        """stream_options should NOT be added for non-streaming requests."""
+        data = {"stream": False, "model": "gpt-4"}
+        _apply_stream_options_logic(
+            data, {"always_include_stream_usage": True}, "acompletion"
+        )
+        assert "stream_options" not in data