ACN is a three-letter acronym that may refer to:
- Accenture (NYSE: ACN)
- Acetonitrile
- Achnasheen railway station (National Rail code: ACN), a United Kingdom railway station
- Acn, abbreviation for the orchid genus Acineta
- ACN Inc., multi-level marketing company selling telecommunications services
- Acrylonitrile
- Action Congress of Nigeria, political party of Nigeria
- Africa Cup of Nations, biennual football tournament held in Africa and organised by the CAF
- Agencia Carabobeña de Noticias, news agency based in Valencia, Venezuela
- Aid to the Church in Need, international Catholic charity based in Königstein im Taunus, Germany
- Aircraft Classification Number, ICAO standard number indicating the pavement load imposed by an aircraft
- American Collectibles Network, former name of the American television network now known as Jewelry Television
- Andean Community of Nations
- Anglican Communion Network, missionary organisation based in Pittsburgh, USA
- Ante Christum Natum, Latin equivalent of B.C., seldom used in English
- Application Context Name (Used in Network/Communication protocols per ETSI standards)
- Architecture for Control Networks, network protocol for theatrical control
- Atlantis Cable News (ACN), a fictional news channel on the American HBO drama television series The Newsroom
- Australian Company Number, number issued by the Australian Securities and Investments Commission to registered companies