We surveyed the shallow-water sponges of Ascension Island using scuba diving. In total, we collected 58 sponge specimens from 17 locations at depths of 0.5–30 m. In addition, we compiled historical records of sponges. We describe nine species new to science: Niphates verityae sp. nov., Petrosia (Petrosia) ernesti sp. nov., Monanchora downesae sp. nov., Svenzea weberorum sp. nov., Erylus williamsae sp. nov., Ircinia nolanae sp. nov., Ircinia richardsoni sp. nov., Ircinia simae sp. nov. and Chondrosia browningorum sp. nov. We provide molecular sequences for three of the new species. We have added 50% to the number of known species and added two new genera and one family to the known Ascension Island sponge fauna. Twenty-six species, from 16 genera, and 13 families, are now reported from Ascension's shallow waters. Many of these may be endemic to the island. We discuss the biogeographic affinities of Ascension Island and emphasize the need for additional survey of the sponge fauna of remote islands such as Ascension.