Megophrys montana males can reach 92 mm in SVL while the larger females can grow to 111 mm. These frogs can be identified by the bizarre, elongated "horn" present on each upper eyelid, and a pointed snout. The pupils are vertical with a dark brown iris. There is a fold of skin separating the head from the body. Dorsally, the skin is generally smooth, with one or two pairs of dorsal ridges extending from behind the head down to the groin, but the dorsum may occasionally bear some black tubercles. Numerous tubercles are present on the flanks. The body shape mimics the appearance of a leaf (Lathrop, 2003; Iskandar, 1998). The color is similar to that of dried leaves, ranging from light brown to reddish brown in color (Lathrop, 2003). Young animals may be brick-red in color, with adults usually reddish to dark brown, and occasionally yellowish brown. The venter is mottled with brown and dark cream. A dark triangular blotch occurs behind the eyes. A pair of black tubercles or spots is generally present dorsally, near the insertion of the arms (Iskandar, 1998).

Megophrys montana tadpoles have a funnel-shaped mouth, with turned-up and laterally expanded lips, allowing feeding at the surface of the water (Iskandar, 1998). The tail is elongated, with a rounded tip (Iskandar, 1998). The larval body and tail are brown (Lathrop, 2003).
 
The diploid chromosome number is 26, with five large pairs and eight smaller ones (Iskandar, 1998).