A stone church is recorded on Tjärnö since medieval times, with the earliest written reference dating from 1391. That building burned in 1630, destroying all its wooden fittings, and was rebuilt in 1632. It survived until the 1850s, when it was demolished to make way for the present church.
The current building was constructed in 1854–1855 to designs by Carl-Gustaf Blom-Carlsson. It consists of a nave with a straight-ended chancel to the east, behind which a semicircular, apse-like extension houses the sacristy. To the west stands the tower, containing the porch and main entrance. The roof is a saddle roof, hipped over the sacristy; the nave is roofed in tile while the sacristy roof is covered in red-painted sheet metal.
Among the church's furnishings is a soapstone font dating from the 13th century, made in two parts and just over half a metre tall. Its cylindrical bowl sits on a short stem with plain flat-cut bands, and a drainage hole runs through its centre. The font is attributed to the Østfold-Marker school of Norwegian stonecarving and shows considerable wear and damage.
The octagonal pulpit dates from the same period as the present church, and was given a new staircase rail and base in 1934. The altarpiece was made in the first half of the 17th century, predating the current building and presumably surviving from the earlier church. Two bells cast in Ystad in 1931 hang in the tower.
The organ itself was built by Tore Lindegren and delivered in 1964, but its case, designed by the architect Ragnar Östberg, was retained from an earlier 1904 organ built by Magnussons Orgelbyggeri.