Risby is a small village in W Suffolk, just 3½ miles W of the centre of Bury St Edmunds. The church stands on the main street, E of the village centre. It is of flint and septaria and has a round W tower, a long unaisled nave and a chancel of the same height with a 19thc. N vestry. The tower has been called pre-Conquest, but its earliest diagnostic features are Romanesque; single high lancets with monolithic round heads to N and S and the tall, irregular tower arch and round-headed opening above it. The bell-stage is curiously fenestrated. It has two rows of three round-headed openings to the S, and two rows of two to the N. A single E bell-opening and a 14thc. W window are later insertions, and the battlemented parapet is later still. The nave must be 12thc. too, from the evidence of a blocked N window visible only on the interior. The chancel arch has 12thc. jambs with carved imposts, including two reused as plinths for its bases. The arch itself is steeply pointed and double chamfered, and dates from well into the 13thc., but 12thc. carved voussoirs have been reused on its E face. Also of the 13thc. are a lancet on the N nave wall, both nave doorways (the S under a 15thc. porch) and the S chancel doorway. Another major campaign took place in the first half of the 14thc., when the nave and chancel walls were heightened and buttresses added. Two-light reticulated or Y-tracery windows were inserted on both nave and chancel at this time, and the chancel was given a three-light reticulated E window. On the N nave wall are the remains of 13thc. and 14thc. wallpaintings. Romanesque features described below are the tower and chancel arches.

The Domesday Survey lists two holdings in Risby. Roger de Poitou held 2 carucates of ploughland and 2 acres of meadow formerly held by Wulfmaer, a thegn under Stigand. The abbey of St Edmundsbury held 2 carucates as a manor, and in the same place a free man gave 1 carucate of land, subsequently held by Norman from the abbot. The abbey's holding included a church with 24 acres of free land.

Risby is now in the Barrow Benefice, along with Great and Little Saxham, Denham and Barrow.

The tower arch, to judge from its proportions and the arch profile, must date fromc.1090-1110, and there is no reason to suppose that the capitals and imposts are not original. On the chancel arch, the tall bases and impost blocks would fit with this dating, but the E face voussoirs are at least two decades later, and it may be than an earlier, narrower chancel arch was widened in the 1130s.