Cerberilla affinis is a species of sea slug, an aeolid nudibranch, a marine heterobranch mollusc in the family Aeolidiidae.

[2] It was described as a variety by Bergh, 1888 but elevated to species status by Burn, 1966.

It has been reported from localities in the Central Indo-Pacific region to Lord Howe Island, the eastern Australian mainland and New Caledonia and is probably widespread in the West Pacific.

[4] All Cerberilla species have a broad foot and the cerata are long and numerous, arranged in transverse rows across the body.

Two species from the Indian Ocean, Cerberilla africana Eliot, 1903 (East Africa) and Cerberilla moebii (Bergh, 1888) - Mauritius are similar in colour.