Owing to the dynamic operation mode of urea selective catalytic reduction (urea-SCR) systems, advanced control strategies are required to improve urea dosing control. A new control-oriented model presentation of urea-SCR systems is developed in this study. A novel controller based on the triple-step non-linear method is designed. The controller drives the non-linear system with time-varying parameters to track the variable ammonia coverage ratio. Unlike the existing triple-step non-linear method, the third design procedure in the proposed method is adjusted as an H error feedback control. The proposed method provides a concise design process so that derivation of the control law can be simple and straightforward. The robustness of the controller against measurement noises and system uncertainties is analysed. A transient simulation is conducted to evaluate the effectiveness of the proposed control strategy.