P2map publish

Screenshot of the p2map_publish.exe interface with an example map

If you are uploading a Portal 2 map to Steam Workshop that was built in Hammer, then you must upload it with a separate utility called p2map_publish.exe, found in \SteamApps\common\Portal 2\bin\ as part of the Portal 2 Authoring Tools.

Usage is fairly straightforward -- click Add to add an entry for your map and upload a map thumbnail and BSP file.

If you wish to include custom assets (textures, models, sounds) then you will need to pack those files into the BSP using a tool like bspzip before uploading to the Workshop.