The new Bishop of Rome was born on September 14, 1955, in Chicago, Illinois, to Louis Marius Prevost, of French and Italian descent, and Mildred Martínez, of Spanish descent. He has two brothers, Louis Martín and John Joseph.

He spent his childhood and adolescence with his family and studied first at the Minor Seminary of the Augustinian Fathers and then at Villanova University in Pennsylvania, where in 1977 he earned a Degree in Mathematics and also studied Philosophy.

On September 1 of the same year, Prevost entered the novitiate of the Order of Saint Augustine (O.S.A.) in Saint Louis, in the Province of Our Lady of Good Counsel of Chicago, and made his first profession on September 2, 1978. On August 29, 1981, he made his solemn vows.