O'Gorman moved to Mexico to work for a British mining company in 1895. Following ill-health from working in mining areas, O'Gorman became a chemist. He met and married his distant cousin in Mexico, Encarnación O'Gorman. They had four children, architect Juan, historian Edmundo, Margarita and Tomás. In his 1973 autobiography, his son Juan recounted the family's experience of the Mexican revolution and the bravery and piety of O'Gorman in protecting his family.