Ctenochaetus cyanocheilus was first formally described in 2001 by the American ichthyologist John Ernest Randall and the New Zealand biologist Kendall Clements with its type locality given as the lagoon between Enewetak and Parry Islands in the Enewetak Atoll, Marshall Islands.

There are numerous small yellow spots on the head and the anterior part of the body.

There is a thin yellow ring around the eyes and the snout is tipped with blue lips.

[5] Ctenochaetus cyanocheilus is found in the Western Pacific Ocean from Sumatra and Peninsular Malaysia east to American Samoa and the Line Islands, north to the Ogasawara Islands of Japan and south to New Caledonia, Tonga and the Great Barrier Reef.

[1] The yelloweye bristletooth is found solitarily at depths between 1 and 60 m (3 ft 3 in and 196 ft 10 in) on areas of dense coral growth on inner and outer reefs, grazing on algae.