MMX may refer to:
- 2010, in Roman numerals
- MMX (instruction set), a single-instruction, multiple-data instruction set designed by Intel
- MMX, an album by rapper, Xzibit that has been delayed to 2011 and thus was renamed as "MMXI"
- MMX (Twelfth Night album), a 2010 album by Twelfth Night
- MMX (War from a Harlots Mouth album), a 2010 album by War from a Harlots Mouth
- MMX Miner, a Brazilian mining company
- Malmö Airport, an airport in Sweden (IATA airport code)
- Mega Man X, a series of video games produced by Capcom and the eponymous main character
- Michelson-Morley Experiment, the 1887 experiment attempting to find evidence of the luminiferous aether