Sandford St Martin is a remote village in N Oxfordshire, 6 miles SE of Chipping Norton. It is in the area of the iron-rich Hornton limestone that extends NE from there. The church is thought to date from the late C12th, when it was a chapel of Steeple Barton nearby, and probably consisted of nave and chancel. The narrow N aisle of three bays was added to the nave c. 1200. Extensive alterations in the mid-C13th are believed to have prompted its dedication in 1273. The S aisle was added, the chancel was remodelled and the present chancel arch added, making decorative use of the varying colours of the Horton stone. There is a Decorated S doorway and porch, and a Perpendicular clerestory and W tower. The chancel arch was retained when the chancel was demolished and rebuilt in the C19th. Romanesque features include the Transitional N aisle with two short octagonal piers, the S chancel doorway and a decorated tub font.

The manor was held by Odo, Bishop of Bayeux in 1086, and by Adam, son of Hubert de Ryes, from him. It was rated at 14 hides less one virgate, with 100 acres of meadow, pasture 4 furlongs by 3, and a furlong of spinney. There was also a mill. Later it was held as part of the Steeple Barton manor by the St John family, and remained in their possession until the mid C16th. The church was a chapelry of Steeple Barton throughout the Middle Ages, although it was often called a church because it had a dependent chapelry in Ledwell, and an endowed vicarage. In 1977 it became part of the United Benefice of Westcote Barton with Duns Tew, Sandford St Martin and Steeple Barton.

Sherwood and Pevsner (1974) suggest that the nave piers of the N aisle were originally round and were recut into their octagonal shape. Their sturdy character does contrast with the slimmer ones of the S aisle, erected in the second half of the C13th, but as they have large octagonal capitals to match, this seems unlikely. The eccentric nature of the capital of the first pier, particularly, makes it more likely that this was an original feature, c. 1200.

Most of the motifs on the font that occupy the chevron spaces are incomplete. It seems that the font top must have been trimmed, as noted by CRSBI for the arcaded font at All Saints Church, Sutton Courtenay, Berkshire.