diff --git a/Lib/mimetypes.py b/Lib/mimetypes.py
index 48a9f430d45262..9661d42394242f 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -495,10 +495,10 @@ def _default_mime_types():
         '.so'     : 'application/octet-stream',
         '.oda'    : 'application/oda',
         '.ogx'    : 'application/ogg',
+        '.ai'     : 'application/pdf',
         '.pdf'    : 'application/pdf',
         '.p7c'    : 'application/pkcs7-mime',
         '.ps'     : 'application/postscript',
-        '.ai'     : 'application/postscript',
         '.eps'    : 'application/postscript',
         '.texi'   : 'application/texinfo',
         '.texinfo': 'application/texinfo',
diff --git a/Misc/NEWS.d/next/Library/2025-11-08-13-03-10.gh-issue-87710.XJeZlP.rst b/Misc/NEWS.d/next/Library/2025-11-08-13-03-10.gh-issue-87710.XJeZlP.rst
new file mode 100644
index 00000000000000..62073280e32b81
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-11-08-13-03-10.gh-issue-87710.XJeZlP.rst
@@ -0,0 +1 @@
+:mod:`mimetypes`: Update mime type for ``.ai`` files to ``application/pdf``.