The medieval church of St Mary's was rebuilt in 1826 by G Draper, then rebuilt again in 1934 by Randoll Blacking. The present building is a large brick church with a spacious galleried nave, transepts and chancel.

Littlehampton church is not mentioned in the Domesday Survey. Its general appearance is known from an engraving, showing the building from the NE. Excavations were carried out before the present building was erected, and it was noted that no pre-Conquest material was found. The scallop capital unearthed at that time was datedc.1110 and thought to come from the chancel arch.