Black spiny-tailed iguanas are excellent climbers, and prefer a rocky habitat with plenty of crevices to hide in, rocks to bask on, and nearby climbing branches. They can be fast moving when spooked and will whip with their tails before trying to bite.

They are primarily herbivorous, eating flowers, leaves, stems, and fruit, but they will opportunistically eat different proteins as well. Juveniles tend to be insectivores, becoming more herbivorous as they get older.