Foix (French pronunciation: [fwa] (listen); Occitan: Fois [ˈfujs, ˈfujʃ]; Catalan: Foix [ˈfoʃ]) is a commune, the former capital of the County of Foix. It is the capital of the department of Ariège as it is the seat of the Préfecture of that department. Foix is located in the Occitanie region of southwestern France. It is the second least populous French departmental capital, the least populous being Privas. Foix lies south of Toulouse, close to the borders with Spain and Andorra.

As of 2019, the city had a population of 9,493. It is only the second biggest town in Ariège, the biggest being Pamiers, which is one of the two sub-prefectures, the other being St Girons. Foix is twinned with the English cathedral city of Ripon, with the Spanish towns of Sarroca de Lleida and Lerida and the Andorran capital Andorre-la-Vieille.