The building began as a small Romanesque church in the 1100s, with a nave and tower forming the original core. In the 14th century, ambitious plans were set in motion to rebuild Källunge into one of Gotland's grandest churches. Work progressed as far as constructing an enormous new chancel before the project stalled, reputedly interrupted by outbreaks of plague and the political turmoil associated with the Danish king Valdemar Atterdag in the mid-1300s. The result is a church of striking proportions: a huge Gothic chancel that today serves as the main worship space, while the original small Romanesque nave now functions as a porch or vestibule.
Visitors entering through the tower and nave can see carved stone fragments salvaged from the demolished Romanesque chancel, a tangible reminder of the earlier building that once stood here. The nave portal's carved capitals are decorated with motifs that appear more folkloric than overtly religious in character, an intriguing detail for those interested in medieval stone carving.
Inside, the Romanesque portion of the church retains fragments of wall paintings showing Russian-Byzantine stylistic influence, dated to the 13th century, while the Gothic chancel contains later medieval paintings from the 14th and 15th centuries. Among the church's furnishings, the font dates from the 1100s, making it one of the oldest surviving fittings in the building. A richly decorated altar cabinet from the 1500s originally belonged to Visby Cathedral before being moved here in 1684. The pulpit was made in 1707.
The church also has a pneumatic organ built in 1931 by the Stockholm firm Åkerman & Lund, replacing an earlier instrument installed in 1875 by a local Källunge builder.