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 almost 14,000 inhabitants, it is the fifth most populous commune in the department of Ain.