Nonparametric models do not require any assumptions on the underlying input/output relationship of the system being modeled so that they are highly useful for studying and modeling the nonlinear behaviour of Magnetorheological (MR) fluid dampers. However, the application of these models in semi-active suspension is very rare and most theoretical works available on this topic address the application of parametric models (e.g. Modified Bouc-Wen model).In this paper, a nonparametric MR damper model based on the Restoring Force Surface technique is applied in vehicle semi-active suspension system. It consists of a three dimensional interpolation using Chebyshev orthogonal polynomial functions to simulate the MR damper force as a function of the displacement, velocity and input voltage. Also, a damper controller based on a Signum function method is proposed, for the first time, for use in conjunction with the system controller of a semi-active vehicle suspension. A mathematical model of a semi-active quarter-vehicle suspension using an MR damper is derived. Suspension performance criteria are evaluated in the time and frequency domains in order to quantify the suspension effectiveness under bump and random road disturbance.The simulated results of the present study show that the applied nonparametric MR damper model is able to express the behavior of the damper precisely and the force tracking controller has the capability to track the desired damping force well. Compared with the passive suspension system, the proposed semi-active control strategy improves the suspension performance effectively.