diff --git a/tests/test_type_conversion.py b/tests/test_type_conversion.py
index 26709db0e2..2ebde0f0b3 100644
--- a/tests/test_type_conversion.py
+++ b/tests/test_type_conversion.py
@@ -88,6 +88,15 @@ class SomeEnum(Enum):
     THREE = "three"
 
 
+def test_enum_convertor_already_converted():
+    """If the value is already an enum member, the convertor should return it as-is."""
+    from typer.main import generate_enum_convertor
+
+    convertor = generate_enum_convertor(SomeEnum)
+    result = convertor(SomeEnum.ONE)
+    assert result is SomeEnum.ONE
+
+
 @pytest.mark.parametrize(
     "type_annotation",
     [list[Path], list[SomeEnum], list[str]],
diff --git a/typer/main.py b/typer/main.py
index a825c1b14e..61d2bd1e5f 100644
--- a/typer/main.py
+++ b/typer/main.py
@@ -1447,6 +1447,8 @@ def generate_enum_convertor(enum: type[Enum]) -> Callable[[Any], Any]:
 
     def convertor(value: Any) -> Any:
         if value is not None:
+            if isinstance(value, enum):
+                return value
             val = str(value)
             if val in val_map:
                 key = val_map[val]