As ex officio abbot of the Abbey of Tongerlo he sat in the First Estate of the States of Brabant during the early years of the Dutch Revolt.

Philip II of Spain named Metsius to the see of 's-Hertogenbosch on 16 November 1569, and Pope Pius V confirmed the nomination on 13 March 1570.

Metsius received episcopal consecration at the hands of Maximilian de Berghes, Archbishop of Cambrai, in St Gudula's on 23 April 1570.

As a member of the States of Brabant, Metsius was a signatory to the 1577 Union of Brussels, but his loyalty to the traditional order made him suspect to the rebels.

In 1579, he served as vicar general of the diocese of Namur, while the see was vacant, himself consecrating the new bishop, François de Wallon-Cappelle, in 1580.