House of Gonzaga
Mattei was the second son of Asdrubale Mattei, "Marquis di Giove", of the House of Mattei and his wife Costanza Gonzaga of the House of Gonzaga. His older brother, Girolamo Mattei, became Duca di Giove. He was the nephew of Ciriaco Mattei and Cardinal Girolamo Mattei.