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

[2][3] The type locality for this species is Ceylon (Sri Lanka).

[4][5] Goniobranchus preciosus has a white mantle with three lines of colour at the edge.

[4][7] This species is very similar to Goniobranchus verrieri and most easily distinguished by the white margin to the mantle.

Goniobranchus trimarginatus is also similar, but has white gills and rhinophores and red speckles in the middle of the back.