A fitness ball chair includes a base, a fitness ball, a support tube and a pad. The base is an elastic structure formed by being spirally enclosed and having an opening in the middle of the base. The fitness ball is movably disposed in the base, and a portion of the fitness ball is disposed in the opening to prevent the fitness from falling out. The support tube is provided for connecting the base and the pad and supporting a user's trunk. The fitness ball is positioned and stored in the base. With the elastic design of the base and the softness of the fitness ball, the fitness ball chair provides a good exercise and protection effects to users, and causes no waste of the using space.