In the 13th century Montjoi was the capital of a wide baillie covering twenty parishes. The name of the mother parish of Saint Martin was Puycastèl.
The founding of the walled town of Montjoi by Alphonse de Poitiers dates back to 1255-1256.
In 1287, Montjoi was transferred to King Edward 1st.
In 1580, during the wars of religion, the city was taken in August by the Catholics, then dismantled and ruined.