MMU may refer to:
- Manchester Metropolitan University in England
- Manned Maneuvering Unit, a NASA rocket pack that snaps onto the back of a spacesuit
- Marymount University, a Catholic university in Arlington, Virginia
- Memory management unit, a computer component
- Methane multiple unit, a rail multiple unit vehicle powered by methane
- Mobile Meteorological Unit, a deployable weather forecasting support unit of the British Armed Forces
- MMU, International Air Transport Association code for Morristown Municipal Airport near Morristown, New Jersey
- Mount Meru University in Tanzania
- Multimedia University, a private university in Malaysia
- Myanmar Maritime University
- Mega Man Universe, a game by Capcom
- Milli mass unit, an unofficial unit of mass