The church began life as a private estate chapel serving Arnöberg, the island's principal manor, and its oldest surviving fabric is thought to date from the 13th century. Until 1943 Arnö formed its own parish and administrative district, but the church later passed out of regular congregational use: it was transferred to state ownership in the late 1950s. It is now the property of Enköping parish grouping, maintained by the National Property Board, while formally belonging to Veckholm parish.
The building consists of an elongated nave, with a porch added on the south side in 1647 and a sacristy on the north. A three-sided chancel was added to the east end around the mid-1570s, and about a century later, around 1700, the nave was extended westward by two bays. A detached timber bell tower dating from 1726 stands to the south-east of the church.
Among the furnishings, a font carved from Sigön marble dates to the 15th century, making it one of the older objects in the church. The altarpiece was donated in 1736, and the pulpit, acquired in 1761, is attributed to the Stockholm craftsman Olof Gerdman.
Of particular interest to visitors is the church organ, built in 1828 by the Stockholm organ builder Pehr Zacharias Strand. It is a mechanical instrument with slider chests, and unusually it is still operated using hand-pumped bellows rather than an electric blower, giving a rare glimpse of how organs were played before modern power was introduced.