Rainbow wrasse have long, moderately compressed streamlined bodies, a pointed nose and a small mouth. The first spiny rays of the dorsal fin are longer than the others. Females have brown or red backs (individuals living at greater depths tend to be darker) and white bellies. A yellow or brown stripe with a white stripe above and below decorates the flanks. The fins are either yellow or orange. Males have either green, blue or brown backs with white or yellow bellies. A sinuous red or orange stripe decorates the flanks, often with blue edging. The first 3 elongated dorsal rays have either an orange or red and black spot. Both sexes have a blue spot on the operculum.
The rainbow wrasse is a protogynous hermaphrodite and feeds on molluscs, worms and crustaceans.