JMJ may refer to:
- Jesus, Mary, Joseph
- Jam Master Jay, the DJ of Run-DMC
- Jean Michel Jarre, a French music composer and producer
- Justin Meldal-Johnsen, bass player
- Journées Mondiales de la Jeunesse, the French translation for World Youth Day
- Jornada Mundial de la Juventud, the Spanish translation for World Youth Day
- Jornada Mundial da Juventude, the Portuguese translation for World Youth Day