Leptomantis cyanopunctatus is a medium-sized, slender tree frog. Females reach 40 mm, males are slightly smaller (see photo).

The eyes are large and a sharp ridge runs from the eye to the nostril and to the tip of the snout. Usually there are white spots below the eye on the upper lip. Specimens on the photo are from Mulu and lack that feature.

Blue spots are present in the groin region and on the backside of the thigh, often on the ventral side of the thigh and parts of the belly too. The tadpoles and details of reproduction, such as clutch size are unknown.