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

[1] This species is known only from Eastern Australia (Northern New South Wales and Southern Great Barrier Reef).

Nembrotha rosannulata is a large dull green nembrothid that grows to at least 12 cm in length.

The pustules are black and each is surrounded by a pink ring which give this species its characteristic colour pattern - and name.

Present information suggest that this nudibranch feeds exclusively on the stalked ascidian Sigillina cyanea.