Ségny, also written Segny, is a commune in the Ain department in eastern France.
Ségny is situated in the east of the department, in a district of the Lake Geneva / River Rhône basin known as the Pays de Gex. It lies on the important RN 5 trunk road from Paris to Geneva and is just five minutes by road from Geneva Cointrin International Airport. A local bus service connects Ségny to Geneva city centre, which is some away.
Ségny became a member of the Pays de Gex Community of Communes on 1 January 1996. The commune is bordered by Cessy to the north, Versonnex to the east, Prévessin-Moëns and Ornex to the south, and Échenevex and Chevry to the west.