Though related to the giant Megatherium, Hapalops was much smaller, measuring about 1 metre (3.3 ft) in length. Like most extinct sloths it is categorized as a ground sloth, but it is believed that the smaller size of Hapalops allowed it to engage in some climbing behaviors.
It had a robust body, short skull and long limbs with large, curved claws. When it did visit the ground the animal probably walked on the knuckles of its forelimbs, like a gorilla. Hapalops had very few teeth with no incisors, the mandible included only four pairs of teeth.
Hapalops represents a taxonomic nightmare in need of revision with approximately 30 different species assigned to the genus, most of which are likely superfluous.