The catalogue records all species and infraspecific taxa of benthic marine algae or seaweeds known for the mainland coast of West Africa (northern boundary of Western Sahara southwards to the southern boundary of Namibia), and the western Atlantic islands between Madeira and the Salvages in the north to Ascension and St Helena in the south, including those lying relatively close to the African mainland. In all over 32 mainland countries and islands are covered. Genera, species and infraspecific taxa are arranged alphabetically within the green algae, brown algae and red algae. Under the currently accepted name there are others that have been commonly used for it in earlier publications on West Africa. Mentioned are all countries and islands from which it has been recorded with reference given to the most recent literature source. Taxonomic, nomenclatural or other information is provided where needed or a reference given to a source of such information. In total 1195 species are now accepted (202 green algae, 200 brown algae, 793 red algae) compared to 2013 recognized in lists published over the past 40 years. Despite the considerable progress made in our knowledge of West African seaweeds over this period there are countries and islands that are little-explored phycologically; no records are traced for the Democratic Republic of the Congo (=Zaire), Rio Muni (Equatorial Guinea) and Cabinda. The seaweed floras of most major island archipelagos are significantly more diverse (e.g. Canary Islands, 646 spp) than the mainland coast where just under 300 species are known for a 4,000 km length of shoreline (Gambia to southern Angola). One new combination is made, namely Chondrophycus glanduliferis (Kütz.) Prud'homme & D.M.John.