A developer going by the handle XDA_Conan repackaged the last Facebook Beta (v11.4) with updated API endpoints. This is often referred to as the "New Facebook Experience" for WP8.1.
Features:
Download location: Archive.org (Search: Facebook_Lumia_Refresh_Unsigned.xap) facebook windows phone xap new
Do not expect a fully functional "new" Facebook XAP.
The only reliably working method in 2025+ is a WebView wrapper pointing to Facebook's basic HTML site. Official API-based XAPs are permanently broken. A developer going by the handle XDA_Conan repackaged
If you need this for archival or demonstration purposes, follow the Web Wrapper creation steps above. For actual social networking, upgrade to an Android/iOS device or use a PC browser. Download location: Archive
Search the "Windows Phone 8.1 Development" section. Users often upload .xap files to Google Drive or Mega. Look for threads titled "Last working Facebook XAP."