diff --git a/pydantic/json_schema.py b/pydantic/json_schema.py
index c81a2899c3..b957846cef 100644
--- a/pydantic/json_schema.py
+++ b/pydantic/json_schema.py
@@ -1195,7 +1195,9 @@ def typed_dict_schema(self, schema: core_schema.TypedDictSchema) -> JsonSchemaVa
         with self._config_wrapper_stack.push(config):
             json_schema = self._named_required_fields_schema(named_required_fields)
 
-        extra = config.get('extra', 'ignore')
+        extra = schema.get('extra_behavior')
+        if extra is None:
+            extra = config.get('extra', 'ignore')
         if extra == 'forbid':
             json_schema['additionalProperties'] = False
         elif extra == 'allow':
diff --git a/tests/test_json_schema.py b/tests/test_json_schema.py
index 105732eb43..227e674d0f 100644
--- a/tests/test_json_schema.py
+++ b/tests/test_json_schema.py
@@ -2406,6 +2406,23 @@ class Model(TypedDict):
     }
 
 
+def test_typeddict_with_extra_behavior_allow():
+    class Model:
+        @classmethod
+        def __get_pydantic_core_schema__(cls, source_type: Any, handler: GetCoreSchemaHandler) -> CoreSchema:
+            return core_schema.typed_dict_schema(
+                {'a': core_schema.typed_dict_field(core_schema.str_schema())},
+                extra_behavior='allow',
+            )
+
+    assert TypeAdapter(Model).json_schema() == {
+        'type': 'object',
+        'properties': {'a': {'title': 'A', 'type': 'string'}},
+        'required': ['a'],
+        'additionalProperties': True,
+    }
+
+
 def test_typeddict_with_extra_ignore():
     class Model(TypedDict):
         __pydantic_config__ = ConfigDict(extra='ignore')  # type: ignore
@@ -2419,6 +2436,22 @@ class Model(TypedDict):
     }
 
 
+def test_typeddict_with_extra_behavior_ignore():
+    class Model:
+        @classmethod
+        def __get_pydantic_core_schema__(cls, source_type: Any, handler: GetCoreSchemaHandler) -> CoreSchema:
+            return core_schema.typed_dict_schema(
+                {'a': core_schema.typed_dict_field(core_schema.str_schema())},
+                extra_behavior='ignore',
+            )
+
+    assert TypeAdapter(Model).json_schema() == {
+        'type': 'object',
+        'properties': {'a': {'title': 'A', 'type': 'string'}},
+        'required': ['a'],
+    }
+
+
 def test_typeddict_with_extra_forbid():
     @pydantic.dataclasses.dataclass
     class Model:
@@ -2434,6 +2467,23 @@ class Model:
     }
 
 
+def test_typeddict_with_extra_behavior_forbid():
+    class Model:
+        @classmethod
+        def __get_pydantic_core_schema__(cls, source_type: Any, handler: GetCoreSchemaHandler) -> CoreSchema:
+            return core_schema.typed_dict_schema(
+                {'a': core_schema.typed_dict_field(core_schema.str_schema())},
+                extra_behavior='forbid',
+            )
+
+    assert TypeAdapter(Model).json_schema() == {
+        'type': 'object',
+        'properties': {'a': {'title': 'A', 'type': 'string'}},
+        'required': ['a'],
+        'additionalProperties': False,
+    }
+
+
 @pytest.mark.parametrize(
     'annotation,kwargs,field_schema',
     [