Alet Cathedral (Cathédrale Notre-Dame d'Alet) was a Roman Catholic church located in the town of Alet-les-Bains in Languedoc, France.

The Diocese of Alet was one of several bishoprics created in 1317 in the wake of the suppression of the Cathars.

In Alet the bishops were also the abbots of the already existing monastery there and the cathedral of Our Lady (Notre-Dame) was built next to the abbey.

The cathedral's stone ruins, which were listed as a monument historique in 1862, remain a spectacular sight.

[1] As the main cathedral was for so long in ruins, part of the monastic buildings were used as an emergency substitute.