Like nearby Wiggonholt Church, which it resembles, Greatham Church was erected in about 1100 to serve the sparsely populated marshlands next to the River Arun between Pulborough and Amberley.
 The hamlet was an agricultural community from the Saxon era, and shepherds would have formed the bulk of the early congregation.
 The Amberley Wild Brooks Site of Special Scientific Interest is nearby.
 Rubble and brickwork from nearby Roman sites was incorporated in the walls, which are aligned at odd angles and do not match in length or thickness.

The original east window was blocked later, and two lancet windows were inserted in its place in the 13th century.
 Similar windows were added to the north and south walls at the same time.
 The 12th-century entrance in the north wall was also bricked up, but its stone jambs are still visible.

Minimal restoration was performed in the 19th century, in contrast to many other Sussex churches, although the original bell-turret was replaced by one topped with a spire.
 A new entrance, set in a porch, was added on the south side, and a vestry was built onto the north wall—although this was removed in the mid-20th century.
 Most of the internal fittings are early 19th-century.
 When the vestry was being built, five soldiers were found buried next to the church wall: they had been killed at the Battle of Greatham Bridge during the English Civil War.
Like nearby Wiggonholt Church, which it resembles, Greatham Church was erected in about 1100 to serve the sparsely populated marshlands next to the River Arun between Pulborough and Amberley.  The hamlet was an agricultural community from the Saxon era, and shepherds would have formed the bulk of the early congregation.  The Amberley Wild Brooks Site of Special Scientific Interest is nearby.  Rubble and brickwork from nearby Roman sites was incorporated in the walls, which are aligned at odd angles and do not match in length or thickness.
The original east window was blocked later, and two lancet windows were inserted in its place in the 13th century.  Similar windows were added to the north and south walls at the same time.  The 12th-century entrance in the north wall was also bricked up, but its stone jambs are still visible.
Minimal restoration was performed in the 19th century, in contrast to many other Sussex churches, although the original bell-turret was replaced by one topped with a spire.  A new entrance, set in a porch, was added on the south side, and a vestry was built onto the north wall—although this was removed in the mid-20th century.  Most of the internal fittings are early 19th-century.  When the vestry was being built, five soldiers were found buried next to the church wall: they had been killed at the Battle of Greatham Bridge during the English Civil War.
Greatham Church