An apparatus and a method for controlling motion of a vehicle to improve turning motion performance are provided. The processor determines a riding position of a user, receives information about a steering angle of the vehicle, and outputs a vehicle control signal with regard to turning motion performance according to at least one of a phase difference between a yaw rate and lateral acceleration or a lateral slip angle with respect to the riding position, based on the received steering angle. A controller controls the vehicle in accordance with the vehicle control signal. The apparatus provides a passenger of the vehicle with optimal turning motion performance.