A three-wheeled vehicle has an auxiliary steering system which is made up of a front frame, a rear frame, a bearing element, a gear set, and a transmission element. The gear set comprises a first gear and a second gear. The first gear is fastened with the front frame while the second gear is fastened rotatably with the rear frame such that the second gear is engageable directly or indirectly with the first gear. The front frame can be caused to swivel in relation to the rear frame by means of the second gear which is actuated by an angular motion of the front fork of the vehicle when the handlebar of the vehicle is turned. The transmission element serves to transmit the angular motion of the front fork to the second gear. The auxiliary steering system is therefore capable of causing the center of gravity of a rider of the vehicle in motion to move toward a direction in which the handlebar of the vehicle is turned, thereby causing the centrifugal force exerting on the vehicle rider to be canceled out.