Built in Romanesque style during the late 1100s or in the 1200s, Gårdeby kyrka is one of the older grey-stone churches of the region. It follows a simple medieval plan of nave, narrower chancel and a semicircular apse, and has no tower. A sacristy was added north of the chancel, probably in the late medieval period, while the church's overall Romanesque character has otherwise remained largely unaltered since the Middle Ages.
Rather than a traditional altarpiece, the apse holds a wooden sculpture of the Good Shepherd, carved by Eva Spångberg and dated 1990, giving the ancient interior an unexpectedly modern focal point.
Other furnishings reflect several centuries of parish life. An octagonal oak font, partly stained black, was made and donated in 1664 by a local captain. The pulpit, acquired in 1839, had originally been given to another nearby church at the end of the seventeenth century before coming to Gårdeby. A painted altarpiece from 1841, depicting Christ in Gethsemane, was created by Per Berggren, though this now serves alongside rather than in place of the modern sculpture.
The entrance arrangements changed in the nineteenth century: the old south doorway was closed up in 1841, when the present west portal was opened. The church also has a small organ, originally built in the 1880s and rebuilt behind its historic case in the 1950s.