Fitzpatrick (John) is born in Boston.

The son of an Irish immigrant father and Boston-born mother, John Fitzpatrick attends Boston Latin School, studies for the priesthood in Montreal and Paris, and is ordained in 1840. He serves as a pastor in Cambridge, then becomes bishop of Catholic archdiocese of Boston on August 16, 1846, presiding over a period of dramatic expansion due to increased immigration from Ireland and is credited with improving the relationship between Boston Catholics and Yankees. Fitzpatrick dies on February 13, 1866. He is buried initially in the cemetery chapel of St. Augustine, then his remains are subsequently moved to a crypt in the Cathedral of the Holy Cross.