Terrestrisuchus was a small, thin, lizard-like creature with long legs, bearing little to no resemblance to modern crocodiles, which are its distant relatives. It had a length of 0.75 to 1 metre (2.5 to 3.3 ft) and a weight of 15 kilograms (33 lb). The shape of the legs suggests that it was able to run fast. Its tail was particularly long, about twice the length of the head and body combined, and may have been used as a balance allowing the animal to rear up and run on its hind legs alone for brief periods.
The legs were positioned directly beneath the body, meaning ancestral crocodiles such as Terrestrisuchus were cursorial and thus, their legs worked as pairs for galloping. Pseudo-galloping can be seen in modern crocodiles as they are known to use paired walking in rare but speed-dependent situations. Fossil evidence also shows that they were digitigrade, supporting their weight on only digits, or fingers.