diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index d64f678d235b6f..2760772390baaa 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -277,7 +277,7 @@ def _hostinfo(self):
         return hostname, port
 
 
-_UNSPECIFIED = ['not specified']
+_UNSPECIFIED = sentinel("_UNSPECIFIED")
 _MISSING_AS_NONE_DEFAULT = False
 
 class _ResultBase:
diff --git a/Misc/NEWS.d/next/Library/2026-05-09-10-50-00.gh-issue-149083.56s2W-.rst b/Misc/NEWS.d/next/Library/2026-05-09-10-50-00.gh-issue-149083.56s2W-.rst
new file mode 100644
index 00000000000000..d9c2fa85b5d8a7
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-05-09-10-50-00.gh-issue-149083.56s2W-.rst
@@ -0,0 +1,2 @@
+The private ``_UNSPECIFIED`` sentinel in :mod:`urllib.parse` is now an
+instance of :class:`sentinel`.