The church is one of the smallest in Wiltshire. It has chequered walls of flint rubble and ashlar, and comprises a chancel and a nave without a division between them. The 12thc. font and a lancet window in the north wall suggest an early origin, but other windows and the west and south doorways are of dates from the late 15th to the early 17thc.

A chaplain of 'Fifield' recorded at a date perhaps in the mid 12thc. and a rector collated to 'Fifield' by the bishop of Salisbury in or before 1291 probably served Fifield Bavant church. There was a rector in 1305. Like its neighbours the church may have been built as a chapel dependent on Broad Chalke church. The suffix Bavant, the surname of 14thc. lords of the manor, was apparently not attached to the name of parish or manor until the 15thc. The church of St Martin was so called in 1496, and may have been so from or before the grant of 1267 of a Martinmas fair at Fifield Bavant.

Pevsner compares the scallops on the underside to other Wiltshire fonts at Etchilhampton, Everleigh, Longbridge Dervill, Nettleton, Norton, Sutton Benger and Tockenham.

Buckler illustrates a font at Fifield as a tub without a shaft. Although he shows it as undecorated, an annotation says “carved with intersecting arcade” and a crude attempt was made to illustrate this arcading. This font is not the one that now exists in the church.