To achieve trajectory tracking for uncertain systems with arbitrary relative degree and disturbances, robust control designs are proposed to treat the system uncertainties included external disturbance, the system state, and control input. In this research, the proposed control approaches can maintain the boundedness of the system state and drive the system outputs arbitrarily close to the desired reference outputs, and the most general and simple control formulation is used to achieve global tracking. On the other hand, robust observer designs are proposed to estimated required state information of the control system, and the observer-based output-feedback design is realized on the basis of the robust observer. Moreover, a noise-free control scheme is proposed to improve of performance the feedback control; the modified design removes the undesirable peaking phenomenon and generates a chattering-free control signal even in a noisy environment.