Theloderma asperum is a small frog with a head that is broader than the body and slightly wider than long. The snout is rounded and slightly longer than the diameter of the eye, with nostrils positioned closer to the tip of the snout than to the eye. The tympanum is prominent and large, while there is no supratympanic fold present. The skin on the back and sides is rough, characterized by small conical warts or tubercles. Its arms are of moderate length, featuring hands with rudimentary webbing at the base, and the legs are also moderately sized.