Nembrotha mullineri is a species of colourful sea slug, a dorid nudibranch, a marine gastropod mollusk in the family Polyceridae.

Nembrotha mullineri is a white-black nembrothid that grows to at least 50 mm in length.

The body is creamy-white, with longitudinal black-brown lines.

The rhinophores and gills are black.

Nembrotha mullineri eats colonial ascidians.