Hypplectrus unicolor has a deep body and head which is highly laterally compressed with a straight forehead and a rather short snout and a protrusible upper jaw.

It has an angular preoperculum which has serrations on its edge and a number of small forward pointing spines on its lower margin close to the angle.

[3] The body is greyish white to yellow in colour with the back being darker, with a sizeable black saddle-like marking on the base of the caudal fin, this extends over the lateral line on each side.

Horizontal, iridescent blue lines run along the head, occasionally these extend as far as front edge of the pelvic fins.

It is normally found at depths between 3 and 25 metres (9.8 and 82.0 ft)>It is a carnivorous species which has a diet largely consisting of crustaceans and smaller fishes.