It is also the only existing building with a stone vaulted ceiling in the southern hemisphere. The cathedral is listed on the Queensland Heritage Register.
The cathedral was designed in the Gothic revival style by John Loughborough Pearson, one of England's leading church architects of the late 19th century and bears similarities to Truro Cathedral in Cornwall, also designed by Pearson, although the architecture of St John's is more decidedly French Gothic in inspiration. The external walls are of randomly arranged brown, pink and mauve Brisbane tuff stone from the O’Connelltown Quarry in the (now) suburb of Windsor, while the interior is primarily dressed sandstone (Helidon freestone) from Helidon near Toowoomba.