FLB
- .FLB, file format for Format Libraries for the Papyrus (software) bibliographic application.
- Faint little ball (flb), a gene first studied in Drosophila
- First Liberty Bank and Trust, the subsidiary of Community Bank, N.A. in Northeast Pennsylvania
- Flashlight Brown, a Canadian punk rock band from Guelph, Ontario
- FLB, an abbreviation for the Favourite-longshot bias, an observation that gamblers bet more heavily on longshots than the odds would recommend
- Front de Libération de la Bretagne
- Lebanese Basketball Federation, the top basketball league in Lebanon