diff --git a/pydantic_ai_slim/pydantic_ai/profiles/google.py b/pydantic_ai_slim/pydantic_ai/profiles/google.py
index 9178d7dd43..3859d76347 100644
--- a/pydantic_ai_slim/pydantic_ai/profiles/google.py
+++ b/pydantic_ai_slim/pydantic_ai/profiles/google.py
@@ -49,7 +49,6 @@ def transform(self, schema: JsonSchema) -> JsonSchema:
             )
 
         schema.pop('title', None)
-        schema.pop('default', None)
         schema.pop('$schema', None)
         if (const := schema.pop('const', None)) is not None:
             # Gemini doesn't support const, but it does support enum with a single value
diff --git a/tests/models/test_gemini.py b/tests/models/test_gemini.py
index 0b95bedeb5..7d628df31a 100644
--- a/tests/models/test_gemini.py
+++ b/tests/models/test_gemini.py
@@ -194,7 +194,7 @@ async def test_require_response_tool(allow_model_requests: None):
 
 async def test_json_def_replaced(allow_model_requests: None):
     class Axis(BaseModel):
-        label: str
+        label: str = Field(default='<unlabeled axis>', description='The label of the axis')
 
     class Chart(BaseModel):
         x_axis: Axis
@@ -213,8 +213,14 @@ class Locations(BaseModel):
         {
             '$defs': {
                 'Axis': {
-                    'properties': {'label': {'title': 'Label', 'type': 'string'}},
-                    'required': ['label'],
+                    'properties': {
+                        'label': {
+                            'default': '<unlabeled axis>',
+                            'description': 'The label of the axis',
+                            'title': 'Label',
+                            'type': 'string',
+                        }
+                    },
                     'title': 'Axis',
                     'type': 'object',
                 },
@@ -268,17 +274,27 @@ class Locations(BaseModel):
                                 'items': {
                                     'properties': {
                                         'lat': {'type': 'number'},
-                                        'lng': {'type': 'number'},
+                                        'lng': {'default': 1.1, 'type': 'number'},
                                         'chart': {
                                             'properties': {
                                                 'x_axis': {
-                                                    'properties': {'label': {'type': 'string'}},
-                                                    'required': ['label'],
+                                                    'properties': {
+                                                        'label': {
+                                                            'default': '<unlabeled axis>',
+                                                            'description': 'The label of the axis',
+                                                            'type': 'string',
+                                                        }
+                                                    },
                                                     'type': 'object',
                                                 },
                                                 'y_axis': {
-                                                    'properties': {'label': {'type': 'string'}},
-                                                    'required': ['label'],
+                                                    'properties': {
+                                                        'label': {
+                                                            'default': '<unlabeled axis>',
+                                                            'description': 'The label of the axis',
+                                                            'type': 'string',
+                                                        }
+                                                    },
                                                     'type': 'object',
                                                 },
                                             },