Wooden church, equal-armed cross church with chamfered interior corners. Korpilahti church stands on a high hill above a village that has grown up on the northern shore of the narrow Kirkkolahti inlet, which belongs to Päijänne. The classicist wooden church is in the form of an equal-armed cross with chamfered inner corners and a central tower.
The transept arms have tympanum gables. The altarpiece "Come unto me" was painted by Vilho Sjöström in 1904. The altar furnishing surrounding the painting was moved to the sacristy during the interior renovation designed by Alvar Aalto in 1927. The church interior was also renewed in e.g. 1992 under the direction of M. Huusari.
B.A. Thulén's organ dates from 1904. The separate bell tower was built in 1885. The parish's earlier churches stood on the cemetery adjacent to the church. On the southern slope of the church hill runs Martinpolku, the old main street of the church village. The old building stock along it, former commercial buildings and private residences, still forms a coherent streetscape.
By the road there is also the lower section of the old bell tower built in 1777, which now serves as a local heritage museum. Korpilahti church harbour has for centuries been the terminus of the waterway and winter road. The boat harbour below the church and the village residents' marina still reflect the significance of inland waterway traffic for church villages in lake Finland.