It was built of coursed flint sometime between 1100-1150. It was enlarged and re-consecrated in 1215 after the signing of Magna Carta. It was extended to the west in the 13th century, and later to the east, creating a chancel. A west tower was added in the late 15th century. The north wall was demolished in the late 18th century to create a north aisle.
A major fire on 8 June 1978 destroyed parts of the church, but left the tower and Norman chapel almost intact. The church was restored by Edward Cullinan with the inclusion of elements of its former structure. The north wall contains a Gothic Revival east window. The church was re-dedicated in February 1984, with the original building now named as the Langton Chapel. St Mary's Barnes is a thriving Christian community with an electoral roll of 350 and strong links across the local community. Along with the parishes of St Michael and All Angels, Barnes and Holy Trinity Barnes it forms the Barnes Team Ministry and the current Team Rector is Rev Richard Sewell.
Major General Roger Elliott was buried in the churchyard on 21 May 1714.