In this study, we present a robust backstepping approach for the control problem of the variable speed wind turbine with permanent magnet synchronous generator. Specifically to overcome the negative effects of parametric uncertainty, of both mechanical and electrical sub-systems, a differentiable robust controller has been proposed. The proposed methodology ensures the generator velocity tracking error to uniformly approach a small bound where practical tracking is achieved. Stability of the overall system is ensured by Lyapunov-based analysis techniques. Simulation studies are presented to illustrate the feasibility and efficiency of the proposed controller.