BSU is a three-letter acronym that may refer to:
- Baptist Student Union
- Behavioral Sciences Unit, the former name for the Federal Bureau of Investigation's Behavioral Analysis Unit
- British Seafarers' Union
- Britannia Staff Union
- Federal Bureau for Maritime Casualty Investigation (Bundesstelle für Seeunfalluntersuchung, BSU)
Universities
- Baku State University
- Ball State University
- Batangas State University Apolinario R. Apacible School of Fisheries (BatSU)
- Bath Spa University
- Belarusian State University
- Bemidji State University
- Benguet State University (BengSU)
- Boise State University
- Bowie State University
- Bukidnon State University
- Bulacan State University (BulSU)
- Bridgewater State University