After he was ordained as a priest, he became a lector of Christian theology at the University of Bologna. He later taught theology at the University of Ferrara, and then in Venice. He was a distinguished preacher, renowned for his knowledge of Augustine of Hippo and Thomas Aquinas, and preached throughout Italy. Cardinal Ercole Gonzaga made Bertani his theologian.
On November 28, 1537, he was elected Bishop of Fano. He attended the Council of Trent from February 4, 1546 until March 3, 1547. He was appointed to the Roman Curia on March 29, 1547. He successfully negotiated the return of Camerino to the Papal States from Guidobaldo II della Rovere, Duke of Urbino. In 1546, the Council of Trent sent him as envoy to Charles V, Holy Roman Emperor to settle the dispute about moving the council to Bologna. From June 9, 1548 until August 1550, he was nuncio extraordinary to the emperor, charged with resolving the dispute about Piacenza following the violent death of Pier Luigi Farnese, Duke of Parma. He also successfully settled a dispute between the emperor and Francis I, Duke of Saxe-Lauenburg. Pope Paul III intended to make him a cardinal, but the pope died before he could do so.