The church was built around 1100 and has kept much of its medieval character despite repeated alterations. It originally had a narrower chancel, built in the later twelfth century, and was probably converted into a hall church in the fourteenth century when the nave was extended eastward. The nearly square nave seen today dates from about 1500, with the sacristy and a porch added around the same period.
In the early sixteenth century the nave was widened to double its original breadth, and six new vaults were built across two aisles, replacing earlier fifteenth-century vaulting. This major expansion may have been linked to the growing workforce at the Åkers styckebruk ironworks, and possibly also to the abandonment of the nearby Ärja church, whose parishioners then turned to Åkers kyrka. The nave is slightly narrower at its south-west corner, thought to reflect reuse of the older porch walls during rebuilding. A steep saddle roof covers the nave, and the shingled, tarred roofs and spire were renewed in 1918.
Inside, round-arched windows light the broad nave, and the altar is flanked by two windows to the east. Most of the medieval wall and vault paintings have since been limewashed over. The altar cabinet dates from 1474 and was fitted with a new central section in 1957, including a figure of St Peter by the sculptor Erik Sand. According to one source, the font, dated to around 1150, is the church's oldest surviving object, though its style suggests a mid-thirteenth-century date.
The pulpit is said to have been a gift from King Gustav II Adolf in 1629. The present pews date from 1953, when the church also received later gallery structures. The current organ was built in 1917 by E. A. Setterquist & Son of Örebro, replacing an eighteenth-century instrument by Pehr Schiörlin; it was later enlarged in the 1950s.
The churchyard, enclosed by a hedge and a dry stone wall, also contains a mortuary chamber, a burial chapel from 1928, a detached bell tower from 1689, and a lychgate.