The Diocese of Varaždin (Latin: Dioecesis Varasdinensis) is a Latin ecclesiastical territory or diocese of the Catholic Church in northern Croatia. The diocese is centred in the city of Varaždin. It is a new diocese, having only been erected on July 5, 1997, from the Archdiocese of Zagreb. Bishop Marko Culej was the first to be head of the diocese. Bishop Bože Radoš is the current bishop of Varaždin.
The Church of the Assumption of Mary into Heaven was built in 1646 and was proclaimed a cathedral on September 28, 1997.