FNS may stand for:
- Federated Naming Service, a system for uniting various name services under a single interface for the basic naming operations
- Finnish Navy Ship, the designator given to all ships in the Finnish Navy
- Food and Nutrition Service, an agency of the United States Department of Agriculture
- Fox News Sunday, a Sunday morning interview show on the Fox Broadcasting Company and the Fox News Channel
- Friday Night SmackDown, a professional wrestling television show for World Wrestling Entertainment
- Frontier Nursing Service, an organisation providing healthcare services
- Fuji Network System
- Financial Network Services Pty LTD an Australian company that provided the BANCS Banking System