diff --git a/changelog/69901.fixed.md b/changelog/69901.fixed.md
new file mode 100644
index 000000000000..c28474dd27fd
--- /dev/null
+++ b/changelog/69901.fixed.md
@@ -0,0 +1 @@
+Fixed `salt.utils.functools` `namespaced_function`/`alias_function` dropping keyword-only argument defaults in copied function
diff --git a/salt/utils/functools.py b/salt/utils/functools.py
index 224d096957c4..d7dbe4b7e28b 100644
--- a/salt/utils/functools.py
+++ b/salt/utils/functools.py
@@ -61,6 +61,9 @@ def namespaced_function(function, global_dict, defaults=None, preserve_context=N
         closure=function.__closure__,
     )
     new_namespaced_function.__dict__.update(function.__dict__)
+    if function.__kwdefaults__ is not None:
+        # Only Py 3.13+ accept this in FunctionType.__new__
+        new_namespaced_function.__kwdefaults__ = function.__kwdefaults__.copy()
     return new_namespaced_function
 
 
@@ -76,6 +79,9 @@ def alias_function(fun, name, doc=None):
         fun.__closure__,
     )
     alias_fun.__dict__.update(fun.__dict__)
+    if fun.__kwdefaults__ is not None:
+        # Only Py 3.13+ accept this in FunctionType.__new__
+        alias_fun.__kwdefaults__ = fun.__kwdefaults__.copy()
 
     if doc and isinstance(doc, str):
         alias_fun.__doc__ = doc
diff --git a/tests/pytests/functional/utils/functools/test_alias_function.py b/tests/pytests/functional/utils/functools/test_alias_function.py
new file mode 100644
index 000000000000..80647f72adee
--- /dev/null
+++ b/tests/pytests/functional/utils/functools/test_alias_function.py
@@ -0,0 +1,11 @@
+from salt.utils.functools import alias_function
+
+
+def test_kwarg_defaults_preserved():
+    def func(_arg, *, default="foo"):
+        return default
+
+    func2 = alias_function(func, "func2")
+
+    assert func(None) == "foo"
+    assert func2(None) == "foo"  # pylint: disable=not-callable
diff --git a/tests/pytests/functional/utils/functools/test_namespaced_function.py b/tests/pytests/functional/utils/functools/test_namespaced_function.py
index 283a722a87c7..f423f1393250 100644
--- a/tests/pytests/functional/utils/functools/test_namespaced_function.py
+++ b/tests/pytests/functional/utils/functools/test_namespaced_function.py
@@ -130,3 +130,13 @@ def foo():
         "for removal in 3008.0 (Argon) and no longer does anything for the function "
         "being namespaced."
     )
+
+
+def test_kwarg_defaults_preserved():
+    def func(_arg, *, default="foo"):
+        return default
+
+    func2 = namespaced_function(func, globals())
+
+    assert func(None) == "foo"
+    assert func2(None) == "foo"  # pylint: disable=not-callable