Carnaby church is first mentioned in a grant to the Priory (1148 - 53). The church consists of chancel, nave, south aisle and west tower. It is built mainly of stone with some flint and cobble parts constructed of brick. According to Bulmer's History: 'This church is a melancholy example of the cheeseparing policy which too frequently exhibited itself in the restoration of ecclesiastical edifices after the Reformation.
Only the circular font which has a carved ornament with a pattern of lozenges and a cobble moulding above, has survived from the Norman church. The earliest parts are south aisle, aisle arcade and the tower arch (13th century).There may have been a north aisle but no traces of it remains. The north wall of the nave is mainly brick (16th century). There are two paired lancet windows in the south aisle, one light being of an early example of plate tracery, made by piercing the spandrel with an inverted trefoil. The aisle arcade has five pointed arches on octagonal piers, three of the moulded capitals having nail-head ornament, - - - the most westerly is converted into the entrance: possibly when the south porch was removed in 1830. The tower arch is all that remains of a 13th century tower. The present 15th century tower is of three stages topped by an embattled parapet. It contains perpendicular windows at the belfry stage and a west window and a narrow embattled transom.
During the 16th and 17th centuries the nave and chancel were in disrepair. Restoration began about 1680, and the chancel was nearly completed in 1719 (wholly built of brick), and now is small and plain, with the remnants of a wooden ceiling. It contained a small east window, now blocked up. The chancel arch may be 13th century, and is unusually wide and low.
In 1830 more repairs were carried out: the south porch was probably removed, the aisle was re-roofed and new square-headed windows cut in the north wall, later replaced by traceried Gothic windows, but one survives in the chancel. In 1966 the slates of the roof were replaced by pantiles, and a new ceiling was put in the nave.
There is an incised inscription in Latin on the second arcade pier from the west, marking the burial place of Walteri Uppiby (13th or 14th century), which translates as 'here lies the body of Walter Uppiby, whose soul God set free.' The Uppiby certainly held land in Carnaby in the early 14th century. A wall plaque commemorates Isabella Humphrey (d. 1910), school mistress for 37 years. This is above the font, along with a plaque to those who died in the 1914 - 18 war. The 19th century pulpit is of stone and is highly ornate.
In 1552 there were three bells (still three in 1968), two dated 1639 and one 1693, one of the former was made by John Conyers. In 1855 the latter bell was badly cracked but was restored in 1892, through the efforts of the vicar who brought over a German craftsman to carry out the work. There are now only two bells working.
In 1764 Communion was administered 4 times a year, but the number receiving it was about 12. In 1871 it was administered monthly, and in 1884 every 6 weeks to 6 - 8 persons. The registers are dated from 1653 and complete.
There are very few memorials in the church. A flat stone in the chancel records the death of Francis Vickerman Esq., 'a lover of learning and a pattern of piety, AD 1616.' Also, there is a fragment to a member of the same family, and one to Annas, wife of a member of the Boynton family, who died in AD 1623.
On the north chancel wall are two discreet plaques. One of the well-known Harold Conner, churchwarden for 32 years, and the other to Audrey Featherstone, organist for a long time.
There have been recent repairs to the chancel roof.
Carnaby is mentioned in the Domesday Book (1087), as Cherendebi (cherend means the truster and the final syllable in Norse 'bi' meaning 'building'.)