diff --git a/Lib/pathlib.py b/Lib/pathlib.py
--- a/Lib/pathlib.py
+++ b/Lib/pathlib.py
@@ -180,7 +180,9 @@
         if not s:
             return os.getcwd()
         if _getfinalpathname is not None:
-            return self._ext_to_normal(_getfinalpathname(s))
+            keep_ext_prefix = bool(self._split_extended_path(s)[0])
+            s = _getfinalpathname(s)
+            return s if keep_ext_prefix else self._ext_to_normal(s)
         # Means fallback on absolute
         return None
 
diff --git a/Lib/test/test_pathlib.py b/Lib/test/test_pathlib.py
--- a/Lib/test/test_pathlib.py
+++ b/Lib/test/test_pathlib.py
@@ -1879,6 +1879,12 @@
         p = P(BASE, "dirC")
         self.assertEqual(set(p.rglob("FILEd")), { P(BASE, "dirC/dirD/fileD") })
 
+    def test_resolve_ext_prefix(self):
+        P = self.cls
+        p = P(BASE)
+        self.assertEqual(BASE, str(p.resolve()))
+        p = P(pathlib._windows_flavour.ext_namespace_prefix + BASE)
+        self.assertEqual("\\\\?\\" + BASE, str(p.resolve()))
 
 if __name__ == "__main__":
     unittest.main()