Cait Sith is fun-loving and playful, but cowardly and a poor fighter. He is an anthropomorphic remote-controlled plush toy cat standing just over three feet tall with short black fur and a white stomach and face. He wears a short red cape and white gloves and a small crown. Cait Sith does not possess any outward robotic features although he is still recognized as such.

As he is merely a robot controlled by Reeve Tuesti, Cait Sith's character can be difficult to perceive. Cait Sith does act noticeably different from Reeve, in particular, his speech patterns are looser, and in the English versions he has a Scottish accent while Reeve does not, and in the japanese versions, he speaks with the unique accent of Reeve's original Kansai dialect.

Cait Sith often refers to himself in the first person, and, as it would be impractical for Reeve to control Cait Sith directly all the time, he has a sort of artificial intelligence.