This paper presents the development of a robust active suspension systems based on a quarter-car model with consideration of system nonlinearities. The sliding mode control with a filtered feedback scheme is exploited to design an active suspension controller, which can improve ride comfort and road handling performance simultaneously. Kalman filter is designed to estimate the state responses as required for active force calculation. The designed controller is applied to the CarSim vehicle model in order to evaluate its effectiveness. Besides, the robustness of the proposed approach is also investigated for vehicle parameters variation. The results of time and frequency responses indicate the improved ride comfort without causing any problem in suspension working limits.