In 1557 he was appointed to the Great Council of Mechelen, the highest law court in the Habsburg Netherlands.

[1] In 1560 Drieux was named first bishop of the newly founded diocese of Leeuwarden, his appointment confirmed in 1561.

On 13 November 1569 he received episcopal consecration in Mechelen from Maximilien de Berghes, archbishop of Cambrai, assisted by Cornelius Jansen and Franciscus Sonnius.

In the night of 28–29 October 1577, while in Ghent for a meeting of the States of Flanders, Drieux was placed under arrest together with several other leading opponents of the Dutch Revolt, including the bishop of Ypres, Martin Rythovius.

He was released on 14 August 1581, as part of a prisoner exchange, and spent time as a refugee in Tournai, Kortrijk, and Oudenaarde.