Apethorpe church lies at the E end of the village, to the NE of Apethorpe Hall, former seat of the Earls of Westmorland. The building comprises a W tower (dated 1633), a nave flanked by N and S aisles, a S porch, a chancel and a S chapel (dated 1621). The fabric dates largely from the late 15thc. and early 17thc., and a single chevron voussoir re-set in the facing of the N aisle is the only hint that an earlier structure stood on the site. The S chapel (Mildmay Chapel) contains one of the finest and most imposing 17thc. tombs in England: that of Sir Anthony Mildmay, attributed to the sculptor Maximilian Colt. The base of a cross shaft fragment of indeterminate date, possibly 13thc. or 14thc., stands in the churchyard to the S of the porch.
In 1086 Apethorpe was part of the King's manor of Nassington (which had a priest). Apethorpe church was probably comprehensively rebuilt by Sir Guy Wolston, who acquired the parish in the late 15thc., and set about building Apethorpe Hall. The estate was acquired by Sir Walter Mildmay, an official in the royal service, in 1551, and remained in the Mildmay family until the male line failed, when Sir Francis Fane, Earl of Westmoreland from 1624, married the heiress, Mary Mildmay.