OMM may refer to:

• O'Melveny & Myers, a US law firm with a worldwide practice
• Object memory model, a structure model for digital object memories
• The Observer Music Monthly, the British monthly music magazine found in The Observer newspaper
• Obstacle mobility model, a type of mobility model
• Of Mice and Men, a novella written by Nobel Prize-winning author John Steinbeck
• Of Mice & Men (band), (often abbreviated OM&M) an American metalcore band
• Of Monsters and Men, an Icelandic indie band
• Old Man Murray, a gaming website
• OMM, a godlike character with a visual representation resembling Jesus in the film THX 1138
• One Magnificent Morning, an American programming block that airs Saturday mornings on the owned-and-operated stations and affiliates of The CW
• The One Million Masterpiece, the world's largest collaborative art project
• The Original Mountain Marathon, a multi-day running event and a precursor to adventure racing
• One Million Moms, a U.S. conservative group
• Open music model, a business model for the digital distribution of music
• The QualiPSo OpenSource Maturity Model
• Order of Military Merit (Canada), a Canadian military honour (post-nominal letters)
• Organisation météorologique mondiale, French for World Meteorological Organization
• Organização da Mulher Moçambicana, Portuguese for Organization of Mozambican Women
• Osteopathic manipulative medicine, a core technique of osteopathy and osteopathic medicine in the United States
• Outer mitochondrial membrane