Rebiba was presented to the bishopric of Motula by the Emperor Charles V, and verified by Pope Paul IV on 12 October 1551. He served as Governor of Rome in 1555. He was named a cardinal on twenty December 1555, and on 13 April 1556 appointed Archbishop of Pisa. Medici was appointed archbishop on fifteen June 1620. He served on missions for Duke Cosimo II, to the Emperor Rudolf, to Matthias of Hungary, Sigismund of Poland, and Philip of Spain.