— In this paper, we present a trajectory tracking control algorithm for an autonomous motorcycle for the DARPA Grand Challenge. The mathematical dynamic model of the autonomous motorcycle is based on the existing work in modeling a bicycle and is extended to capture the steering effect on self-stabilization. The trajectory tracking control is designed using an external/internal model decomposition approach, and the motorcycle balancing is developed by the nonlinear control methods. The motorcycle balancing is guaranteed by the system internal equilibria calculation and by the trajectory and system dynamics requirements. The motion planning algorithms are based on the fused global positioning systems (GPS) and on-board computer vision systems information. The proposed control system is validated by numerical simulations, which are based on a real prototype motorcycle system.