St Mary and All Saints has a chancel, an aisled nave and a S tower. Of the late-medieval building on the site, the 14thc S tower porch and 15thc N nave aisle have survived, possibly associated with the church erected by Sir Robert Knollys (d. 1407). A ruthless and immensely wealthy professional soldier, Knollys died in Sculthorpe, his chief Norfolk manor, having rebuilt the church. The chancel was replaced in 1846-47 and the S nave aisle with three-bay arcade was added in 1860-61. The elaborately carved Romanesque font is one of a distinctive and localised group, closely related in terms of their ornament and style. Two short chip-carved fragments on the sill of the W window of the N aisle (in 1985) constitute the building's only other Romanesque sculpture.

Sculthorpe, in Gallow hundred, is calculated to have had some 46 households at the time of the Domesday survey and would thus have been a very large settlement compared with others in the survey. A church with 60 acres is recorded here in Domesday Book. Before the Norman Conquest, Toki of Walton was lord. At the time of the Domesday survey, William de Warenne was lord and tenant-in-chief. The church paid tithes to Lewes Priory, William's foundation in Sussex.

The other three fonts in Norfolk that are considered to constitute a stylistic group with Sculthorpe are at Shernbourne, Toftrees and South Wootton. In Bond's view, they were 'unsurpassed in Europe ... the work of a great, unknown, original genius.'

The beasts on the Sculthorpe font have been described as 'grotesque semi-animal, semi-human heads' (Dukinfield Astley (1908), 223)

Sources differ as to the amount of land belonging to the church, some giving the area as 40 acres, others as 60. There may have been confusion over the order in which the Roman numerals were written.

The antiquary John Leland (1503-52) observed that Sculthorpe was a college with a master and 6 or 7 priests and with a hospital attached to it, housing 16 poor men and women (Blomefield (1807), 176).

The chancel was replaced in 1846-47 by London architects, the brothers Raphael and Joshua Brandon. The S nave aisle with three-bay arcade was added in 1860-61 by Thomas Jekyll.