Goniobranchus tasmaniensis is a species of colourful sea slug, a dorid nudibranch, a marine gastropod mollusc in the family Chromodorididae.

It is one of a group of similar red-spotted chromodorids from south-eastern Australia which form a mimicry ring.

[4][5] Goniobranchus tasmaniensis is a chromodorid nudibranch which has a translucent white mantle with scattered orange or red spots.

The edge of the mantle is opaque white and somewhat swollen and ruffled in resting animals.

[7] This species feeds on the sponge Darwinella gardineri.