It is a large snake, reaching more than 2 m (6+1⁄2 ft) in total length. The front teeth of the upper jaw and the lower jaw are strongly enlarged.
The body is slender and laterally compressed. Dorsally it is tannish with reddish-brown or dark brown crossbands. There is a dark streak behind the eye on each side of the head. The venter is whitish, heavily marbled with dark brown.
The smooth dorsal scales are arranged in 23 or 33 rows at midbody, and those in the vertebral row are strongly enlarged. Ventrals 248–290; subcaudals 114–165.
Boiga cynodon is an oviparous species, with sexually mature females laying eggs, 6-12 per clutch.
