The Archdiocese of Mechelen–Brussels is a Latin Church ecclesiastical territory or archdiocese of the Catholic Church in Belgium. It is the primatial see of Belgium and the centre of the ecclesiastical province governed by the Archbishop of Mechelen–Brussels, which covers the whole of Belgium. It was formed in 1559 and the bishop has a seat in two cathedrals, St. Rumbold's Cathedral in Mechelen and the Cathedral of St. Michael and St. Gudula in Brussels. The current archbishop is Luc Terlinden, who was installed in September 2023.

The Catholic Church in Belgium, part of the global Catholic Church in Belgium, is under the spiritual leadership of the Pope, the curia in Rome and the Episcopal Conference of Bishops.