St Mary's Church, Barnes, is the parish church of Barnes, formerly in Surrey and now in the London Borough of Richmond upon Thames. It is a grade II* listed building.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.
Coordinates 51°28'29.914" N -0°14'30.697" E