Abj is an abbreviation for abject, abjunction, and abjuration. ABJ may also refer to:
- ABJ (motorcycle), a 1950s bike built by AB Jackson Cycles of Birmingham, England
- Adler–Bell–Jackiw anomaly, in theoretical physics
- Abaeté Linhas Aéreas, Brazil airline ICAO code
- Félix-Houphouët-Boigny International Airport, Abidjan, Côte d'Ivoire IATA code
- Aka-Bea language, ISO 639 code
- The American Business Journal, monthly business publication
- Anything But Joey, pop-rock band
- Bachelor of Arts in Journalism, degree at the University of Georgia, United States