Tagging is supported since LaunchBar 6, released June 11, 2014.
You either send a file or a selection of files from Finder to LB (
space) or select a file (or – with nightly build 6.1 – a selection of files) within LB.
tab, type a part of the Finder tag name and add the tag by pressing
return. You have also the option to replace existing tags with the new tag.
You can display a file’s tags by pressing
→ after selecting the file in LB.
LaunchBar 6.3 added support to work with multiple tags at once.