When Dr. Robotnik built his base in the Special Zone, he began sending Badniks across Mobius to destroy the Star Posts. The Sonic Badnik - along with a number of other unique Badniks - was dispatched to the Emerald Hill Zone to destroy the Star Posts there and to capture Sonic and claim him as an organic battery. The Sonic Badnik soon found its target and attacked, using moves very similar to Sonic's own. Sonic appeared to be losing the battle when Tails intervened, but as they moved in to strike the Badnik, they collided with each other. The Sonic Badnik took this opportunity to grab Sonic with coils extending from inside its chassis, which pulled Sonic inside the robot. Robotnik arrived with a squad of Badniks and gloated to Tails about the apparent success of his plan. However, Sonic had not been brainwashed by the Badnik he was now installed within and was in full control. He attacked Robotnik and threatened to spin-attack him whilst holding his moustache if he didn't release all the Badniks' victims. Robotnik complied and the Badnik shells self-destructed, including Sonic's.
- The Sonic Badnik appears to be a re-design of the Silver Sonic robot assigned to the Death Egg, although it is larger and clunkier than Silver Sonic.
- In STC #42, Robotnik had built a new Badnik based on Sonic that was stored in his lab. It had no legs, only a booster engine, and carried guns in its fingers and mouth. It also had a grenade for a nose. This Badnik was never used.