The most probable source of the name is the shape of the island - it resembles a wedding cake. Another theory is that bird droppings on the island gave the appearance of icing on a cake. Apparently the island was also formerly called Gingerbread Island.
In 1975, "Wedding Cake Island" was the title of a popular surf music instrumental single by Australian rock music band Midnight Oil. The track was re-released in 1980 on the EP Bird Noises. It was also covered by legendary the Australian surf group The Atlantics on the album Delightful Rain in 2006. The Atlantics often include it as part of their live set, with Midnight Oil's blessing.