In 1504, he was appointed bishop of Płock by Alexander Jagiellon, King of Poland (1501-1506). At the lord's disposition he twice was sent to Rome to speak to Pope Julius II. In 1518 he was sent by King Sigismund I to the Diet of Augsburg to solicit aid against the Ottoman Turks, and subsequently to Rome to seek the mediation of Pope Leo X regarding the conflict between Poland and the Teutonic knights. The negotiations proved very dilatory and treaties were not signed until after Vitellius died.