The church of St. Peter was built between 1773-1778 to replace the earlier made in the 17th century. In the Middle Ages there was a chapel in the Karksi castle dedicated to apostle Peter. Some of the remaining walls of castle ruins were used in the construction of the present church. Karksi church is known of its slanting tower that due to bad soil has inclined one meter to the west.
The first written record of church in Danmark locality date back to the year 1291. Close to the church are several stones with a Christian text and cross inscribed. The oldest parts of the present red-brick church are from the 1300s. In the late 1400s the church was enlarged to the appearance it has today. The church has been modified both internally and externally several times, among other things after the fires in 1699 and 1889. There are lot of well-preserved mural paintings in the walls.