The church consists of a rectangular nave with a broad, cross-arm-like extension in the middle of the south side of the nave, which is crowned by a somewhat narrower tower structure. The south side, facing the town centre, forms the church's main façade.
The church interior is large and spacious. The interior has undergone several changes over time. Originally, there were galleries on all sides of the church except towards the east. The chancel was smaller and darker, and was flanked by a church porch to the north and a sacristy to the south, both of which were contained within the church's existing outer walls.
The major alteration works were carried out in 1875–76 and 1932–33. In 1875–76 the chancel was enlarged and fitted with a new large window facing east and a new altar decoration. At the same time, the north gallery was removed, a hipped roof replaced a barrel-vaulted ceiling, and the current pulpit was added. During the 1932 renovation, the chancel was once again redesigned.
The window was covered over with the artist Olle Hjortberg's monumental altarpiece "På vandring mot den eviga staden" ("On a journey towards the eternal city"). At the same time, the pulpit was altered and the roof was rebuilt.
The church contains a medieval font of soapstone. It has been preserved from Åmål's first church, which was built of wood. Åmåls kyrka is one of the diocese's larger churches and forms a significant feature and landmark in the townscape. Its location next to the former grammar school (läroverket) and the headmaster's residence reflects the historically strong connection between the church and the school system.