ABU is a three-letter acronym that may refer to:
- Airman Battle Uniform, a new utility uniform for the U.S. Air Force.
- Asia-Pacific Broadcasting Union
- Atlantic Baptist University, a Christian university located in Moncton, New Brunswick, Canada
- l'Association des Bibliophiles Universels, a digital library project that publishes French works in the public domain
- Haliwen Airport (IATA airport code: ABU) in Atambua, Indonesia
- Ahmadu Bello University, a university located in Zaria, Nigeria.
- ABU Garcia, a Swedish producer of sportfishing equipment
- Asymptomatic bacteriuria, bacteria in the urine without signs of a urinary tract infection
- Anyone But United, a phrase referencing how many football fans would rather see any other club besides Manchester United succeed.