Montjoie was founded and fortified in the 13th century around its church, on a road much frequented by wanderers and pilgrims.

It was in 1273, through a charter of customs, that we find evidence of the foundation of the Bastide of Montjoie and its parageage between the Crown of France and the Bishopric of Couserans. The town was built thanks to the King, but its management was left to the Bishop. This situation reinforced the Bishop's independence from the County of Comminges.