In 1225, the first documented mention of a church in Greiz occurred when Bishop Engelhard of Naumburg awarded the patronage of the churches to the bailiffs of Weida in a legal dispute.

As an extension to the Lower Castle (with the tower on the east facade above the chancel), a court church in the classicist style was built in 1736 by the Saxon master builder Christian Friedrich Schuricht. Together with the Lower Castle and the Gymnasium, the town church, as the former court church of the Princes of Reuss of the older line, forms a unique classicist ensemble.

The town church of St. Mary was rebuilt in 1805 after the great town fire of 1802, in which the existing Silbermann organ was destroyed. The tower (64 m high) was rebuilt true to the original, but the dome was not added until 1827. The interior of the three-nave church is divided by mighty Corinthian columns, between which are three galleries. With the three galleries, the church today can accommodate about 1,000 visitors.

On the first gallery, the magnificent coffin of Heinrich VI, Count of Reuss-Obergreiz (1649-1697), commemorates the hero of Greiz who fell in the Battle of the Turks at Zenta in 1697 and has been housed in a small memorial chapel since 1941. The eastern end of this former court church is crowned by a pulpit altar with rich classicist furnishings. The town church of St. Mary received a Kreutzbach organ in 1881, which was rebuilt and expanded by the Jehmlich brothers from Dresden in 1919. It is one of the largest organs in the Thuringian region.