The church was designed by eminent Victorian architect John Norton, completed in 1896 and consecrated on 17 June 1897 by Edward Bickersteth, the Bishop of Exeter.

[5] The NW-SE orientation of the church does not conform to the usual east–west alignment, possibly a result of a deep bed of clay found at the site when the foundations were laid.

It is largely built of local granite ashlar blocks derived from ruined cottages on the island.

The tower, with an adjoining square stair turret, has battlements, gargoyles at the corners and lancet bell-openings with trefoil heads and slate louvres.

There is a clock face above a niche containing a figure of Saint Helen (bearing an inscription of the Latin form, Helena), over the chamfered, wooden-gated, arch doorway to the porch.

[9] The interior comprises a nave with a porch beneath the tower, and a chancel, with a transept vestry on the north side.

[5] In 2018, a ten-year plan to restore the building and improve facilities within it was completed to create the St Helen's Centre.

In the early part of the twentieth century several newspaper articles, by journalists who had visited the island, gave the name of the church as St Helena - presumably after seeing the inscription on the tower - and other writers started using the name, resulting in the error being repeated in academic books and journals and even official documentation.