diff --git a/CHANGES b/CHANGES
index 9fc0c40f7..a289f5ebc 100644
--- a/CHANGES
+++ b/CHANGES
@@ -45,6 +45,7 @@ Bugs fixed
 * #8315: autodoc: Failed to resolve struct.Struct type annotation
 * #8652: autodoc: All variable comments in the module are ignored if the module
   contains invalid type comments
+* #8693: autodoc: Default values for overloaded functions are rendered as string
 * #8306: autosummary: mocked modules are documented as empty page when using
   :recursive: option
 * #8618: html: kbd role produces incorrect HTML when compound-key separators (-,
diff --git a/sphinx/util/inspect.py b/sphinx/util/inspect.py
index e91e5df96..202e170c1 100644
--- a/sphinx/util/inspect.py
+++ b/sphinx/util/inspect.py
@@ -499,6 +499,19 @@ def is_builtin_class_method(obj: Any, attr_name: str) -> bool:
     return getattr(builtins, name, None) is cls
 
 
+class DefaultValue:
+    """A simple wrapper for default value of the parameters of overload functions."""
+
+    def __init__(self, value: str) -> None:
+        self.value = value
+
+    def __eq__(self, other: object) -> bool:
+        return self.value == other
+
+    def __repr__(self) -> str:
+        return self.value
+
+
 def _should_unwrap(subject: Callable) -> bool:
     """Check the function should be unwrapped on getting signature."""
     if (safe_getattr(subject, '__globals__', None) and
@@ -704,7 +717,7 @@ def signature_from_ast(node: ast.FunctionDef, code: str = '') -> inspect.Signatu
             if defaults[i] is Parameter.empty:
                 default = Parameter.empty
             else:
-                default = ast_unparse(defaults[i], code)
+                default = DefaultValue(ast_unparse(defaults[i], code))
 
             annotation = ast_unparse(arg.annotation, code) or Parameter.empty
             params.append(Parameter(arg.arg, Parameter.POSITIONAL_ONLY,
@@ -714,7 +727,7 @@ def signature_from_ast(node: ast.FunctionDef, code: str = '') -> inspect.Signatu
         if defaults[i + posonlyargs] is Parameter.empty:
             default = Parameter.empty
         else:
-            default = ast_unparse(defaults[i + posonlyargs], code)
+            default = DefaultValue(ast_unparse(defaults[i + posonlyargs], code))
 
         annotation = ast_unparse(arg.annotation, code) or Parameter.empty
         params.append(Parameter(arg.arg, Parameter.POSITIONAL_OR_KEYWORD,
diff --git a/tests/roots/test-ext-autodoc/target/overload.py b/tests/roots/test-ext-autodoc/target/overload.py
index cc4e509f2..35d078b66 100644
--- a/tests/roots/test-ext-autodoc/target/overload.py
+++ b/tests/roots/test-ext-autodoc/target/overload.py
@@ -2,17 +2,17 @@ from typing import Any, overload
 
 
 @overload
-def sum(x: int, y: int) -> int:
+def sum(x: int, y: int = 0) -> int:
     ...
 
 
 @overload
-def sum(x: "float", y: "float") -> "float":
+def sum(x: "float", y: "float" = 0.0) -> "float":
     ...
 
 
 @overload
-def sum(x: str, y: str) -> str:
+def sum(x: str, y: str = ...) -> str:
     ...
 
 
@@ -25,15 +25,15 @@ class Math:
     """docstring"""
 
     @overload
-    def sum(self, x: int, y: int) -> int:
+    def sum(self, x: int, y: int = 0) -> int:
         ...
 
     @overload
-    def sum(self, x: "float", y: "float") -> "float":
+    def sum(self, x: "float", y: "float" = 0.0) -> "float":
         ...
 
     @overload
-    def sum(self, x: str, y: str) -> str:
+    def sum(self, x: str, y: str = ...) -> str:
         ...
 
     def sum(self, x, y):
diff --git a/tests/test_ext_autodoc.py b/tests/test_ext_autodoc.py
index 4ac9381ae..3ff33cea2 100644
--- a/tests/test_ext_autodoc.py
+++ b/tests/test_ext_autodoc.py
@@ -2078,17 +2078,17 @@ def test_overload(app):
         '   docstring',
         '',
         '',
-        '   .. py:method:: Math.sum(x: int, y: int) -> int',
-        '                  Math.sum(x: float, y: float) -> float',
-        '                  Math.sum(x: str, y: str) -> str',
+        '   .. py:method:: Math.sum(x: int, y: int = 0) -> int',
+        '                  Math.sum(x: float, y: float = 0.0) -> float',
+        '                  Math.sum(x: str, y: str = ...) -> str',
         '      :module: target.overload',
         '',
         '      docstring',
         '',
         '',
-        '.. py:function:: sum(x: int, y: int) -> int',
-        '                 sum(x: float, y: float) -> float',
-        '                 sum(x: str, y: str) -> str',
+        '.. py:function:: sum(x: int, y: int = 0) -> int',
+        '                 sum(x: float, y: float = 0.0) -> float',
+        '                 sum(x: str, y: str = ...) -> str',
         '   :module: target.overload',
         '',
         '   docstring',