With the island's new inhabitants at Brownsea Castle and Maryland, as well as existing coastguard station, Waugh had St Mary's built in 1853–54 at his sole expense.

Designed by the architect Mr. Blanchard and built by Charles Wheeler, the foundation stone of the new church was laid by Sir Harry Smith, 1st Baronet on 2 July 1853.

Edward Denison, granted permission in about 1847 for the rector of Studland to use a sail loft at Brownsea Island's coastguard station for divine service on alternate Wednesdays.

[5] In 1908, a small chapel was added onto the church to hold the marble tomb effigy of Charles van Raalte, who owned the island from 1901 until his death in 1908.

[7] During World War II, the western side of Brownsea Island was used as a Starfish site, a night-time decoy intended to divert German bombers away from Poole.

Sunday afternoon services are held each week from Easter to the end of September and the church is also open to visitors to Brownsea Island.

[14][1] The church's three-stage square tower has a battlemented parapet and is surmounted by a small octagonal turret on its north side.

[4][1] All of the interior's original carvings, including the pulpit and reading desk, were carried out by Mr. G. Gynne of Soho, while tablets, inscriptions and stained glass windows were made by Messrs. Baillie and Mayer.

[17] The four-light east window illustrates different scenes in the life of Christ: the transfiguration, the crucifixion, the descent from the Cross and the Ascension of our Lord.

[4] After purchasing Brownsea Island in 1873, George Augustus Cavendish-Bentink lavished the church with a number of additional fittings, including two marble figures depicting winged angels.

His place of burial, along with his wife, who died in 1896, is marked by a monument which has an Italian well-head as its base, over which is an oranmental iron arch with a bronze plaque.

Instead, it was put up for auction by creditors in 1857, along with the rest of the island, after the Waughs' industrial venture there proved a failure and the family fled to Spain.