In 1945, the Viborg Diocese moved to Mikkeli, making the city’s church the cathedral. It underwent renovations in the 1950s, including changes by architect Martti Välikangas. The pulpit was replaced, stained glass images added, and a new organ installed. The church was further renovated in 1983-84, with colorful interior painting and changes to seating. Below, the old boiler room became a crypt, and a small café was added. The bell tower was modernized in 1989, and the historic steps outside were renovated in 1997.