diff --git a/libs/partners/openai/langchain_openai/chat_models/base.py b/libs/partners/openai/langchain_openai/chat_models/base.py
index 142e7eca1a8..c16cffa1abf 100644
--- a/libs/partners/openai/langchain_openai/chat_models/base.py
+++ b/libs/partners/openai/langchain_openai/chat_models/base.py
@@ -2195,6 +2195,50 @@ def _resize(width: int, height: int) -> Tuple[int, int]:
     return width, height
 
 
+def _update_schema_with_optional_fields(input_dict: dict) -> dict:
+
+    def _update_properties(schema: dict):
+        if schema.get('type') != 'object':
+            return
+
+        properties = schema.get('properties', {})
+        required_fields = set(schema.get('required', []))
+
+        for field, field_schema in properties.items():
+            # Remove the 'default' key if it exists
+            field_schema.pop('default', None)
+
+            if field_schema.get('type') == 'object':
+                _update_properties(field_schema)
+
+            if 'allOf' in field_schema:
+                for sub_schema in field_schema['allOf']:
+                    if sub_schema.get('type') == 'object':
+                        _update_properties(sub_schema)
+
+            # if 'anyOf' in field_schema:
+            #     # Check if 'anyOf' contains a 'null' type
+            #     types = [sub_schema.get('type') for sub_schema in field_schema['anyOf']]
+            #     if 'null' not in types:
+            #         field_schema['anyOf'].append({'type': 'null'})
+
+            if field not in required_fields:
+                original_type = field_schema.get('type')
+                if isinstance(original_type, str):
+                    field_schema['type'] = [original_type, 'null']
+                elif isinstance(original_type, list) and 'null' not in original_type:
+                    field_schema['type'].append('null')
+
+                required_fields.add(field)
+
+        schema['required'] = list(required_fields)
+
+    schema = input_dict.get('json_schema', {}).get('schema', {})
+    _update_properties(schema)
+
+    return input_dict
+
+
 def _convert_to_openai_response_format(
     schema: Union[Dict[str, Any], Type], *, strict: Optional[bool] = None
 ) -> Union[Dict, TypeBaseModel]:
@@ -2225,6 +2269,8 @@ def _convert_to_openai_response_format(
             f"'strict' is only specified in one place."
         )
         raise ValueError(msg)
+    if strict:
+        _update_schema_with_optional_fields(response_format)
     return response_format