Couiza (French pronunciation: [kwiza] ⓘ; Occitan: Coisan) is a commune in the Aude department in southern France.

Couiza is located at the foothills of the Pyrenees, on the road between Limoux, going towards Carcassonne and Quillan, going towards Perpignan.

Exposed to an altered oceanic climate, it is drained by the Aude, the Sals , and the Antugnac stream.

The architectural heritage of the town includes a building protected as a historic monument: the castle, listed in 1913.

The railway line from Carcassonne runs here stopping in Limoux and Espéraza on the way but the service is limited.