CGN is a three-letter abbreviation which may stand for:
- CGN (gene), or Cingulin, a human gene located on Chromosome 1
- Compagnie Générale de Navigation sur le lac Léman — a public Swiss company operating boats on Lake Geneva
- Childhood gender nonconformity — a childhood behavioural pattern
- The airport IATA code for Cologne Bonn Airport
- Cogan railway station, Wales; National Rail station code CGN
- A U.S. Navy designation of nuclear-powered guided missile cruisers, such as USS California (CGN-36)
- Carrier-grade NAT, an approach to IPv4 network design where end sites are configured with private network addresses