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

This species was known as Chromodoris decora for many years before it was transferred to the genus Goniobranchus on the basis of molecular (DNA) evidence in 2012.

It occurs in the western Pacific Ocean from Hawaii to the Marshall Islands and New Caledonia.

The tips of the rhinophores and the outer part of the gills is white.

[6] Goniobranchus decorus feeds on sponges of the family Aplysillidae including Chelonaplysilla violacea.