Onchidella nigricans is a species of small, air-breathing sea slug, a shell-less marine pulmonate gastropod mollusc in the family Onchidiidae.

This species occurs in New Zealand, as well as on the coast of south-eastern Australia, where it is common.

[3][4] O. nigricans is a general herbivore feeding on algae.

[5] This species can be found in the intertidal zone on a variety of habitats.

This Onchidiidae-related article is a stub.