This article relies largely or entirely on a single source. (August 2018)
Marini failed to be bishop of Perugia when Pope Paul III died before he could elect him, but his successor, Pope Julius III appointed him the administrator of the diocese of Mantua and bishop of Diocese of Laodicensis in Phrygia (March 5, 1550).
He also served as papal diplomat to Emperor Charles V, and in 1560 Pope Pius IV appointed him bishop of Lanciano (and archbishop in 1562). He was papal legate to the Council of Trent. After being transferred to Alba (1566), appointed apostolic visitor to twenty-five dioceses of Italy.
He collaborated on the formation of the Roman Catechism and was a member of the Roman Breviary reform commission (1568) and of the Roman Missal (1570). On behalf of Pius IV, he reviewed the rules and constitutions of the Clerics Regular of St. Paul (Barnabites).
- "CATHOLIC ENCYCLOPEDIA: Marina". www.newadvent.org. Retrieved 2017-11-27.