diff --git a/litellm/llms/ollama/chat/transformation.py b/litellm/llms/ollama/chat/transformation.py
index cb3080e6534..10bf3736e64 100644
--- a/litellm/llms/ollama/chat/transformation.py
+++ b/litellm/llms/ollama/chat/transformation.py
@@ -171,10 +171,12 @@ class OllamaChatConfig(BaseConfig):
                 if value.get("json_schema") and value["json_schema"].get("schema"):
                     optional_params["format"] = value["json_schema"]["schema"]
             if param == "reasoning_effort" and value is not None:
-                if model.startswith("gpt-oss"):
-                    optional_params["think"] = value
-                else:
-                    optional_params["think"] = value in {"low", "medium", "high"}
+                effort: Final = value.get("effort") if isinstance(value, dict) else value
+                if effort is not None:
+                    if model.startswith("gpt-oss"):
+                        optional_params["think"] = effort
+                    else:
+                        optional_params["think"] = effort in {"low", "medium", "high"}
             ### FUNCTION CALLING LOGIC ###
             # Ollama 0.4+ supports native tool calling - pass tools directly
             # and let Ollama handle model capability detection
diff --git a/litellm/llms/ollama/completion/transformation.py b/litellm/llms/ollama/completion/transformation.py
index b1f69220de7..e8dfb209b19 100644
--- a/litellm/llms/ollama/completion/transformation.py
+++ b/litellm/llms/ollama/completion/transformation.py
@@ -215,10 +215,12 @@ class OllamaConfig(BaseConfig):
             elif param == "stop":
                 optional_params["stop"] = value
             elif param == "reasoning_effort" and value is not None:
-                if model.startswith("gpt-oss"):
-                    optional_params["think"] = value
-                else:
-                    optional_params["think"] = value in {"low", "medium", "high"}
+                effort: Final = value.get("effort") if isinstance(value, dict) else value
+                if effort is not None:
+                    if model.startswith("gpt-oss"):
+                        optional_params["think"] = effort
+                    else:
+                        optional_params["think"] = effort in {"low", "medium", "high"}
             elif param == "response_format" and isinstance(value, dict):
                 if value["type"] == "json_object":
                     optional_params["format"] = "json"
diff --git a/tests/unit/llms/ollama/test_ollama_chat_transformation.py b/tests/unit/llms/ollama/test_ollama_chat_transformation.py
index c7fba21d222..58595502357 100644
--- a/tests/unit/llms/ollama/test_ollama_chat_transformation.py
+++ b/tests/unit/llms/ollama/test_ollama_chat_transformation.py
@@ -1,7 +1,7 @@
 import inspect
 import os
 import sys
-from typing import cast
+from typing import Final, cast
 
 import pytest
 from pydantic import BaseModel
@@ -989,3 +989,43 @@ class TestOllamaStreamingUsage:
         )
 
         assert result.usage is None
+
+
+class TestOllamaChatReasoningEffort:
+    @pytest.mark.parametrize(
+        "reasoning_effort, expected_think",
+        [
+            ("low", True),
+            ("high", True),
+            ("none", False),
+            ({"effort": "medium"}, True),
+            ({"effort": "medium", "summary": "auto"}, True),
+            ({"effort": "none", "summary": "detailed"}, False),
+        ],
+    )
+    def test_reasoning_effort_string_or_dict_maps_to_think(
+        self, reasoning_effort: str | dict[str, str], expected_think: bool
+    ) -> None:
+        optional_params: Final = get_optional_params(
+            model="ollama_chat/qwen3:8b",
+            custom_llm_provider="ollama_chat",
+            reasoning_effort=reasoning_effort,
+        )
+        assert optional_params["think"] is expected_think
+
+    def test_reasoning_dict_without_effort_sets_nothing(self) -> None:
+        optional_params: Final = get_optional_params(
+            model="ollama_chat/qwen3:8b",
+            custom_llm_provider="ollama_chat",
+            reasoning_effort={"summary": "auto"},
+        )
+        assert "think" not in optional_params
+
+    def test_reasoning_dict_gpt_oss_forwards_effort_string(self) -> None:
+        optional_params: Final = OllamaChatConfig().map_openai_params(
+            non_default_params={"reasoning_effort": {"effort": "high", "summary": "auto"}},
+            optional_params={},
+            model="gpt-oss:20b",
+            drop_params=False,
+        )
+        assert optional_params["think"] == "high"
diff --git a/tests/unit/llms/ollama/test_ollama_completion_transformation.py b/tests/unit/llms/ollama/test_ollama_completion_transformation.py
index d6215a742f0..e51e5979deb 100644
--- a/tests/unit/llms/ollama/test_ollama_completion_transformation.py
+++ b/tests/unit/llms/ollama/test_ollama_completion_transformation.py
@@ -2,6 +2,7 @@ import base64
 import io
 import json
 import sys
+from typing import Final
 from litellm._uuid import uuid
 from unittest.mock import MagicMock, patch
 
@@ -775,3 +776,42 @@ def test_transform_request_leaves_unreadable_images_untouched(payload: str) -> N
     data = _transform_image_request(payload, "png")
 
     assert data["images"] == [payload]
+
+
+class TestOllamaConfigReasoningEffort:
+    @pytest.mark.parametrize(
+        "reasoning_effort, expected_think",
+        [
+            ("medium", True),
+            ({"effort": "medium", "summary": "auto"}, True),
+            ({"effort": "none"}, False),
+        ],
+    )
+    def test_reasoning_effort_string_or_dict_maps_to_think(
+        self, reasoning_effort: str | dict[str, str], expected_think: bool
+    ) -> None:
+        optional_params: Final = OllamaConfig().map_openai_params(
+            non_default_params={"reasoning_effort": reasoning_effort},
+            optional_params={},
+            model="qwen3:8b",
+            drop_params=False,
+        )
+        assert optional_params["think"] is expected_think
+
+    def test_reasoning_dict_gpt_oss_forwards_effort_string(self) -> None:
+        optional_params: Final = OllamaConfig().map_openai_params(
+            non_default_params={"reasoning_effort": {"effort": "high", "summary": "auto"}},
+            optional_params={},
+            model="gpt-oss:20b",
+            drop_params=False,
+        )
+        assert optional_params["think"] == "high"
+
+    def test_reasoning_dict_without_effort_sets_nothing(self) -> None:
+        optional_params: Final = OllamaConfig().map_openai_params(
+            non_default_params={"reasoning_effort": {"summary": "auto"}},
+            optional_params={},
+            model="qwen3:8b",
+            drop_params=False,
+        )
+        assert "think" not in optional_params