House of Gonzaga
Mattei was born in 1606, the son of Asdrubale Mattei, "Marquis di Giove", and his wife Costanza Gonzaga (of the House of Gonzaga). He was the older brother of Luigi Mattei; Marquis di Belmonte and military ally of the Barberini and Pope Urban VIII. He was a nephew of Ciriaco Mattei and Cardinal Girolamo Mattei.