Saint-Genis-Pouilly  is a commune in the Ain department within the Auvergne-Rhône-Alpes region of eastern France.

It is located in the Pays de Gex, at the foot of the Jura Mountains. Bordering the Swiss frontier, it is part of the cross-border area of Geneva. With a population of over 12,000 inhabitants, it is one of the ten most populous towns in the department of Ain.

A large portion of CERN, the European laboratory for particle physics, is located within the territory of Saint-Genis-Pouilly; the ALICE experiment is located on the periphery of the town, and the main entrance to the primary CERN campus (Meyrin) and the ATLAS experiment are located only 3 km from the centre of St Genis. CERN is the world’s largest fundamental physics research laboratory and its presence has largely been responsible for the development of the community of Saint Genis since the middle of the 1960s.