diff --git a/changes/3135-PrettyWood.md b/changes/3135-PrettyWood.md
new file mode 100644
index 0000000..643e1f5
--- /dev/null
+++ b/changes/3135-PrettyWood.md
@@ -0,0 +1 @@
+fix `validate_arguments` issue with `Config.validate_all`
diff --git a/pydantic/decorator.py b/pydantic/decorator.py
index 869afee..ca709b4 100644
--- a/pydantic/decorator.py
+++ b/pydantic/decorator.py
@@ -220,15 +220,15 @@ class ValidatedFunction:
 
         class DecoratorBaseModel(BaseModel):
             @validator(self.v_args_name, check_fields=False, allow_reuse=True)
-            def check_args(cls, v: List[Any]) -> List[Any]:
-                if takes_args:
+            def check_args(cls, v: Optional[List[Any]]) -> Optional[List[Any]]:
+                if takes_args or v is None:
                     return v
 
                 raise TypeError(f'{pos_args} positional arguments expected but {pos_args + len(v)} given')
 
             @validator(self.v_kwargs_name, check_fields=False, allow_reuse=True)
-            def check_kwargs(cls, v: Dict[str, Any]) -> Dict[str, Any]:
-                if takes_kwargs:
+            def check_kwargs(cls, v: Optional[Dict[str, Any]]) -> Optional[Dict[str, Any]]:
+                if takes_kwargs or v is None:
                     return v
 
                 plural = '' if len(v) == 1 else 's'
@@ -236,13 +236,19 @@ class ValidatedFunction:
                 raise TypeError(f'unexpected keyword argument{plural}: {keys}')
 
             @validator(V_POSITIONAL_ONLY_NAME, check_fields=False, allow_reuse=True)
-            def check_positional_only(cls, v: List[str]) -> None:
+            def check_positional_only(cls, v: Optional[List[str]]) -> None:
+                if v is None:
+                    return
+
                 plural = '' if len(v) == 1 else 's'
                 keys = ', '.join(map(repr, v))
                 raise TypeError(f'positional-only argument{plural} passed as keyword argument{plural}: {keys}')
 
             @validator(V_DUPLICATE_KWARGS, check_fields=False, allow_reuse=True)
-            def check_duplicate_kwargs(cls, v: List[str]) -> None:
+            def check_duplicate_kwargs(cls, v: Optional[List[str]]) -> None:
+                if v is None:
+                    return
+
                 plural = '' if len(v) == 1 else 's'
                 keys = ', '.join(map(repr, v))
                 raise TypeError(f'multiple values for argument{plural}: {keys}')
diff --git a/tests/test_decorator.py b/tests/test_decorator.py
index cbfc2dd..ea06368 100644
--- a/tests/test_decorator.py
+++ b/tests/test_decorator.py
@@ -1,6 +1,7 @@
 import asyncio
 import inspect
 import sys
+from datetime import datetime, timezone
 from pathlib import Path
 from typing import List
 
@@ -399,3 +400,30 @@ def test_validate(mocker):
         func.validate(['qwe'], 2)
 
     stub.assert_not_called()
+
+
+def test_validate_all():
+    @validate_arguments(config=dict(validate_all=True))
+    def foo(dt: datetime = Field(default_factory=lambda: 946684800)):
+        return dt
+
+    assert foo() == datetime(2000, 1, 1, tzinfo=timezone.utc)
+    assert foo(0) == datetime(1970, 1, 1, tzinfo=timezone.utc)
+
+
+@skip_pre_38
+def test_validate_all_positional(create_module):
+    module = create_module(
+        # language=Python
+        """
+from datetime import datetime
+
+from pydantic import Field, validate_arguments
+
+@validate_arguments(config=dict(validate_all=True))
+def foo(dt: datetime = Field(default_factory=lambda: 946684800), /):
+    return dt
+"""
+    )
+    assert module.foo() == datetime(2000, 1, 1, tzinfo=timezone.utc)
+    assert module.foo(0) == datetime(1970, 1, 1, tzinfo=timezone.utc)