The Malayan krait may attain a total length of 108 cm (about 3.5 ft), with a tail 16 cm (6.3 in) long. Dorsally, it has a pattern of 27-34 dark-brown, black, or bluish-black crossbands on the body and tail, which are narrowed and rounded on the sides. The first crossband is continuous with the dark color of the head. The dark crossbands are separated by broad, yellowish-white interspaces, which may be spotted with black. Ventrally, it is uniformly white.

The Malayan krait is a dangerously venomous species of krait. In mice, the IV LD50 for this species is 0.1 mg/kg. Envenomation rate among this species is very high and the untreated mortality is 70%, although even with antivenom and mechanical ventilation the mortality rate is at 50%.