On his return, Philip II of Spain appointed him first bishop of the newly founded See of Ghent, which dated only from 1559. For a long time he refused to assume the dignity, on account of the difficult conditions in the diocese, and was not preconized until 1568, by Pope Pius V. As bishop he devoted himself especially to checking the advance of Protestantism, and to carrying out the decrees of the Council of Trent.
Upon his return from a journey, Philip II of Spain appointed him as the first bishop of the newly created diocese of Ghent, which had been established just 60 years earlier. For many years, he hesitated to take on the role due to the difficulties faced by the diocese and was not ordained until 1568 by Pope Pius V. As a bishop, he concentrated his efforts on countering the growth of Protestantism and upholding the decisions made at the Council of Trent.