MJB
MJB may refer to:
- Mary J. Blige (born 1971), American singer
- Matthew James Bellamy, a lead guitarist and singer of rock band Muse, composer and songwriter.
- MJB (coffee), an American brand of coffee
- Movement for Justice en el Barrio, a community organization in New York
- Mejit Airport, a Marshall Islands airport with IATA code MJB
- Magic Blue Airlines, a former Dutch airline with ICAO code MJB
- Male Jailbait, a term used online for categorizing male teenagers