There is historic and structural evidence of a Saxon place of worship on the site, and some 11th-century work survives in the chancel, but the present appearance of the church is mostly 13th-century.

In its earliest form, the parish of Eastergate covered 918 acres (372 ha) of flat, flood-prone land on the Sussex coastal plain,[2] about 4 miles (6.4 km) northeast of the modern seaside resort of Bognor Regis and a similar distance southwest of the ancient town of Arundel.

[2] By the following year, it was associated with the Norman Abbey of Séez, whose other holdings in the area included the manors of Atherington (with Bailiffscourt Chapel) and Littlehampton.

Several church historians have come to different conclusions about its origins: it has been suggested that the chancel is Saxon, that the whole building is the one recorded in the Domesday Book, that it is "possibly pre-Conquest", or that (per Gerard Baldwin Brown) it dates from "within 50 years of the Norman conquest" and lacks any "distinctive Saxon features".

[3] Elsewhere, only one window survives from the church's earliest times: a "primitive" narrow opening in the north wall of the chancel.

[10] A modern wooden sculpture of Saint George has also been provided, and a late-20th-century tapestry commemorates the history of Eastergate parish and the church.

[3] St George's Church has a nave with no aisles, a narrower chancel and a bell-turret at the west end of the roof.

[2][4][11] It is an "uncomplicated building with no buttresses"[8] and little ornamentation, although Nikolaus Pevsner described the offset, overhanging bell-turret as "frilly".

[8] Enclosed shingled bell-turrets were uncommon in the Victorian era: the addition of open-sided stone-built bellcotes was more popular.

[3] In the west wall of the nave is a three-light window paid for in 1534 under the terms of a will; it has plain arched heads without cusping.

[1][2] Internal fittings include 18th-century altar rails and a rare pair of priest's stalls in a mixed Gothic and Classical style, dating from the early 19th century.

They face each other across the chancel and consist of paired wooden pillars and an "oddly out of place ... severely Classical" tester.

[2][4] These were "convincingly linked to the 'Lewes Group' of 12th-century wall paintings in the Sussex churches of Hardham, Clayton and Coombes.

It covers the three villages and the surrounding rural area, and hamlets such as Norton, Fontwell, Lidsey and Woodgate.

On special festivals it often accommodates in excess of 150 worshippers[10] Every Sunday morning, Mattins and Holy Communion are celebrated using the Book of Common Prayer.

[23] The present rectory was built in the 1920s and given to the Parish by the Davenport family in 1976 on the main road to Barnham, but two earlier buildings were also used for this purpose.

Vacated by the early 18th century, it became ruinous and was demolished in the 1830s in favour of a Tudor-style flint building on Church Lane.