CMN or cmn may refer to:
- Companies
- Constructions Mécaniques de Normandie, a shipyard in Cherbourg, France
- Corey McPherson Nash, American branding and design firm
- Culture and education
- Canadian Museum of Nature, Ottawa, Canada
- Centre des monuments nationaux, French heritage agency
- College of the Menominee Nation, community college in Wisconsin, USA
- Media
- Canadian Monarchist News, journal of the Monarchist League of Canada
- Catholic Media Network, Philippines radio network
- Compass Media Networks, American radio network
- Other fields
- Certificate of medical necessity, in US healthcare
- Children's Miracle Network, children's charity
- Common Music Notation, open source musical notation software
- The IATA code for Mohammed V International Airport, Casablanca, Morocco
- The ISO 639-3 language code for Mandarin Chinese
- Carmarthen Railway Station (National Rail designation: CMN), in West Wales
- Congenital melanocytic nevus, a skin condition