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, Philip II of Spain designated him as the initial bishop of the newly formed diocese of Ghent, which had only been established in 1559. For a considerable time, he declined to assume the office due to the tough conditions within the diocese and was not consecrated until 1568 by Pope Pius V. As a bishop, he focused particularly on thwarting the spread of Protestantism and enforcing the decrees of the Council of Trent.