The church was constructed in 1938–1939 to designs by the royal palace architect Knut Nordenskjöld, and was consecrated in October 1939. The building cost was met through two diocesan collections. It stands in a meadow surrounded by rocky outcrops, with a white-painted timber exterior on a granite base, and a slate roof covering both the nave and the tower's spire.
A notable architectural feature is the tall church tower with its spire topped by a cross and crown, a symbol said to represent earthly sorrow and Christian triumph. This particular spire design is found on only four churches in Sweden, marking the four compass points of the country: besides Koster in the far west, similar towers stand at Karesuando in the north, Haparanda in the east, and Smygehuk in the south.
Inside, the church has a recessed, barrel-vaulted ceiling extending over both the nave and the narrower chancel, and fixed pews arranged around a central aisle. Most of the fittings date from the time of the church's construction. Above the altar, a round window holds a stained-glass depiction of the Holy City, designed by Yngve Lundström and N. P. Ringström, while the altarpiece, by Gunnar Torhamn, shows Christ preaching to the crowds from a boat on the Sea of Galilee.
Other furnishings of note include a pulpit with a square body and sounding board, made by Conrad Carlman, and a font with a rounded basin on a shaped square stem. The organ was built by the Lindegren organ workshop. A mortuary chapel, partly built into a slope on the opposite side of the road, dates from the 1950s.