Ariège is a department in southwestern France, located in the region of Occitanie. It is named after the river Ariège and its capital is Foix. Ariège is known for its rural landscape, with a population of 153,287 as of 2019. Its INSEE and postal code is 09, hence the department's informal name of le zéro neuf. The inhabitants of the department are known as Ariègeois or Ariègeoises.

In the administrative divisions of France, the department is one of the three levels of government under the national level, between the administrative regions and the communes. Ninety-six departments are in metropolitan France, with an additional five constituting overseas departments, which are also classified as overseas regions. Departments are further subdivided into 333 arrondissements and 2,054 cantons. These last two levels of government have no political autonomy, instead serving as the administrative basis for the local organisation of police, fire departments as well as, in certain cases, elections.