After his formation for the priesthood at the regional seminary of Toulouse in the 1960s, Michel Mouïsse was ordained a priest for the diocese of Albi on December 18, 1966.

He studied at the Notre Dame primary school in Mazamet, the collège in Barral de Castres, the lycée at Saint-Théodard in Montauban, where he obtained his baccalauréat, and then at the University of Toulouse.

In 2010, amid the global economic crisis, Michel Mouïsse called for a "burst of humanity and fraternity" and greater social justice.

[15] In January 2011, with the Middle East amid the Arab Spring, Michel Mouïsse called for peace and dialogue in this part of the world.

[17][18] In the 2014 municipal elections, according to Christian Foucher[19] (the bishopric's communications director), the modified statement was written by the National Front, with passages "against the socialists" and others inciting to "total war" against "jihadist fanatics," On February 4, 2015, a press release (claiming to be written by the bishop) was posted on several extremist websites, denouncing the complicity of the media and the "famous intellectual and political elites" in the attacks on Christian places of worship in Egypt.