Mirepoix, part of the independent fiefdom of Foix, was a stronghold of the Cathars, who held a council here in 1206. Only 3 years later (1209) Simon de Montfort´s armee captured the town after a siege. He gave it to one of his lieutenants, Guy de Lévis. Raymond Roger von Foix reconquered Mirepoix in 1223 and re-installed the Cathar Pierre-Roger de Mirepoix.

After the Treaty of Paris (1229), that ended the Albigensian Crusade and the political autonomy of Occitan, the town was given back to Guy de Lévis, whose son moved the town after a devasting flood (1289) to higher grounds and had it rebuilt as a "bastide". This layout was never changed, so in the center is a large rectangular place, named today "Place du Maréchal-Leclerc".

The nice 19th century market hall and the Cathédrale Saint-Maurice are in the center of the "bastide".

The erection of the Mirepoix Cathedral started in 1298 and the construction continued over centuries. The cathedral completed in the typical "gothique méridional" style was restored in the 19th century by Prosper Mérimée and Eugène Viollet-le-Duc.

The parish church was between 1317 and 1801 the seat of the Bishop of Mirepoix.