The southeastern Arabian Sea (SEAS) is a distinct ecosystem within the northern Indian Ocean, with unique physical, chemical and biological attributes. This paper provides comprehensive documentation on echinoderm diversity in the SEAS at depths of 20 to 1500 m, based on systematic surveys of over 300 sites. A total of 76 species were recorded in the surveys, which included one new species, seven new records for Indian waters and 39 species previously known from nearby areas and recorded for the first time from SEAS. With the addition of the new records from the present study to the 133 species previously reported from the SEAS, the species richness of echinoderms in the SEAS stands at 180 species. Updated checklists of echinoderms in the SEAS are provided.