The design problem of robust stabilizing controllers for nonlinear uncertain systems is considered in this paper. The nominal system is input-output linearizable, and the uncertainty is assumed to be either generalized matching or mismatched. The control design combines differential geometric feedback linearization with the deterministic approach, in which no statistical property of the uncertainty is assumed and used; the only information on the uncertainty, which is needed for the design, is its possible bound. Two robust stabilizing controllers for generalized matching uncertain systems are given. For mismatched uncertain systems, a systematic design procedure is first presented, then four robust stabilizing controllers are given. The robust controllers, which are given in forms of explicit feedback laws based on the nominal system and are parametrized by the robust design parameters related to the bounds of uncertainties, are more practicable than the existing ones in the literature. Numerical examples and simulation results verify the effectiveness of the design method and controllers.