diff --git a/litellm/model_prices_and_context_window_backup.json b/litellm/model_prices_and_context_window_backup.json
index 77244a32f6f..6da93b33d00 100644
--- a/litellm/model_prices_and_context_window_backup.json
+++ b/litellm/model_prices_and_context_window_backup.json
@@ -5661,6 +5661,7 @@
         "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
         "supports_prompt_caching": true,
         "supports_reasoning": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -5680,6 +5681,7 @@
         "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
         "supports_prompt_caching": true,
         "supports_reasoning": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -11779,6 +11781,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -11817,6 +11820,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -11876,6 +11880,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -11895,6 +11900,7 @@
         "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
         "supports_prompt_caching": true,
         "supports_reasoning": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -12008,6 +12014,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -12035,6 +12042,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -12751,6 +12759,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -12789,6 +12798,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -12808,6 +12818,7 @@
         "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
         "supports_prompt_caching": true,
         "supports_reasoning": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -12827,6 +12838,7 @@
         "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
         "supports_prompt_caching": true,
         "supports_reasoning": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -12854,6 +12866,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -12881,6 +12894,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -45884,6 +45898,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_web_search": true
@@ -46008,6 +46023,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_web_search": true
@@ -46032,6 +46048,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -46055,6 +46072,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -46184,6 +46202,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_web_search": true
@@ -46288,6 +46307,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_web_search": true
@@ -70686,6 +70706,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -72193,7 +72214,8 @@
             "search_context_size_low": 0.014,
             "search_context_size_medium": 0.014
         },
-        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'"
+        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
+        "supports_system_messages": true
     },
     "azure/eu/o3-2025-04-16": {
         "deprecation_date": "2026-11-19",
@@ -72212,7 +72234,8 @@
             "search_context_size_low": 0.014,
             "search_context_size_medium": 0.014
         },
-        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'"
+        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
+        "supports_system_messages": true
     },
     "azure/eu/o3-deep-research": {
         "deprecation_date": "2026-11-19",
@@ -72243,7 +72266,8 @@
             "search_context_size_low": 0.014,
             "search_context_size_medium": 0.014
         },
-        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'"
+        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
+        "supports_system_messages": true
     },
     "azure/eu/o4-mini-2025-04-16": {
         "deprecation_date": "2026-11-19",
@@ -72263,7 +72287,8 @@
             "search_context_size_low": 0.014,
             "search_context_size_medium": 0.014
         },
-        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'"
+        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
+        "supports_system_messages": true
     },
     "azure/eu/text-embedding-3-large": {
         "deprecation_date": "2028-02-09",
diff --git a/model_prices_and_context_window.json b/model_prices_and_context_window.json
index 77244a32f6f..6da93b33d00 100644
--- a/model_prices_and_context_window.json
+++ b/model_prices_and_context_window.json
@@ -5661,6 +5661,7 @@
         "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
         "supports_prompt_caching": true,
         "supports_reasoning": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -5680,6 +5681,7 @@
         "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
         "supports_prompt_caching": true,
         "supports_reasoning": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -11779,6 +11781,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -11817,6 +11820,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -11876,6 +11880,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -11895,6 +11900,7 @@
         "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
         "supports_prompt_caching": true,
         "supports_reasoning": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -12008,6 +12014,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -12035,6 +12042,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -12751,6 +12759,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -12789,6 +12798,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -12808,6 +12818,7 @@
         "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
         "supports_prompt_caching": true,
         "supports_reasoning": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -12827,6 +12838,7 @@
         "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
         "supports_prompt_caching": true,
         "supports_reasoning": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -12854,6 +12866,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -12881,6 +12894,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true
     },
@@ -45884,6 +45898,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_web_search": true
@@ -46008,6 +46023,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_web_search": true
@@ -46032,6 +46048,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -46055,6 +46072,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -46184,6 +46202,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_web_search": true
@@ -46288,6 +46307,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_web_search": true
@@ -70686,6 +70706,7 @@
         "supports_prompt_caching": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
+        "supports_system_messages": true,
         "supports_tool_choice": true,
         "supports_vision": false
     },
@@ -72193,7 +72214,8 @@
             "search_context_size_low": 0.014,
             "search_context_size_medium": 0.014
         },
-        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'"
+        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
+        "supports_system_messages": true
     },
     "azure/eu/o3-2025-04-16": {
         "deprecation_date": "2026-11-19",
@@ -72212,7 +72234,8 @@
             "search_context_size_low": 0.014,
             "search_context_size_medium": 0.014
         },
-        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'"
+        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
+        "supports_system_messages": true
     },
     "azure/eu/o3-deep-research": {
         "deprecation_date": "2026-11-19",
@@ -72243,7 +72266,8 @@
             "search_context_size_low": 0.014,
             "search_context_size_medium": 0.014
         },
-        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'"
+        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
+        "supports_system_messages": true
     },
     "azure/eu/o4-mini-2025-04-16": {
         "deprecation_date": "2026-11-19",
@@ -72263,7 +72287,8 @@
             "search_context_size_low": 0.014,
             "search_context_size_medium": 0.014
         },
-        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'"
+        "source": "https://prices.azure.com/api/retail/prices?$filter=serviceName%20eq%20'Foundry%20Models'%20and%20armRegionName%20eq%20'eastus'%20and%20priceType%20eq%20'Consumption'",
+        "supports_system_messages": true
     },
     "azure/eu/text-embedding-3-large": {
         "deprecation_date": "2028-02-09",
diff --git a/tests/unit/llms/openai/test_o_series_transformation.py b/tests/unit/llms/openai/test_o_series_transformation.py
index 9d39dfda60a..a59928d83f2 100644
--- a/tests/unit/llms/openai/test_o_series_transformation.py
+++ b/tests/unit/llms/openai/test_o_series_transformation.py
@@ -6,6 +6,7 @@ import pytest
 
 import litellm
 from litellm import ModelResponse
+from litellm.llms.azure.chat.o_series_transformation import AzureOpenAIO1Config
 from litellm.llms.openai.chat.o_series_transformation import OpenAIOSeriesConfig
 import os
 
@@ -219,3 +220,24 @@ def test_o_series_request_turns_system_into_user_without_touching_the_callers_me
 
     assert [message["role"] for message in body["messages"]] == ["user", "user"]
     assert messages == messages_before
+
+
+@pytest.mark.parametrize(
+    "config",
+    [OpenAIOSeriesConfig(), AzureOpenAIO1Config()],
+    ids=["openai", "azure"],
+)
+@pytest.mark.parametrize("model", ["o3", "o3-2025-04-16", "o4-mini", "o4-mini-2025-04-16", "o3-mini"])
+def test_o_series_keeps_system_role_for_models_that_support_it(config: OpenAIOSeriesConfig, model: str):
+    """o1-2024-12-17 and later reasoning models accept system messages, which the API treats as developer messages
+    (https://platform.openai.com/docs/guides/reasoning, checked 2026-10-28). Rewriting them as user messages drops
+    them to user-level authority"""
+    system_message: Final = {"role": "system", "content": "Be a good bot!"}
+    request: Final = config.transform_request(
+        model=model,
+        messages=[dict(system_message), {"role": "user", "content": "hi"}],
+        optional_params={},
+        litellm_params={},
+        headers={},
+    )
+    assert request["messages"][0] == system_message