The church is a simple medieval hall church with a rectangular chancel, an attached sacristy and a porch, all built of rough stone with decorative brick gables patterned in white against red. Its exterior has changed remarkably little since the late 1400s, apart from the enlargement of some window openings over the centuries.
Inside, three brick vaults cover the nave and chancel, and it is the chancel vault and walls that draw most attention: paintings created around 1500 depict the seven sacraments grouped around a figure of Christ, with blood flowing symbolically from his wounds to each sacrament, a composition based on a Nuremberg engraving of 1490. Elsewhere in the chancel, an Old Testament scene shows Samson wrestling a lion and carrying off the gates of Gaza. Traces of four medieval consecration crosses, marked in oil when the church was dedicated, also survive.
Among the furnishings, a plain 13th-century limestone font and a triumphal crucifix of about 1275 – a type otherwise recorded chiefly on Åland – recall the church's earliest history, while a 14th-century oak sacrament house stands beside the altar. The altarpiece and pulpit both date from the 1640s, gifts of Claes Christersson Horn, then lord of nearby Ekebyholm Castle; the altarpiece's central painting elaborates the same blood-and-water imagery seen in the chancel murals. A brass chandelier of 30 arms, given in 1676 by Bengt Horn, originally hung in the chancel itself.
Outside, a detached 1825 bell tower serves as the main entrance to the churchyard and holds three bells, the oldest cast in 1638 for a church in Finland before being presented to Rimbo. The Horn family's burial chapel of 1805 stands southwest of the church, a reminder of an earlier, abandoned plan by Bengt Horn to build a grander mausoleum on the site. Two runestones stand near the church and a third is built into the chancel's outer wall, evidence of settlement in the area long before the present building was raised.