In this paper, a new robust wavelet time-variant sliding-mode control (RWTVSMC) for an uncertain nonlinear system is presented. The proposed method is composed of two controllers, based on a time variant sliding equation. For this purpose a neural wavelet controller is designed to approximate an ideal controller based on the wavelet network approximation. Also a robust controller is designed to achieve H^∞ tracking performance. New terminologies, rejection parameter and rejection regulator, for filtering all un-modeled frequencies are defined. A time-variant sliding equation based on the time-variant rejection parameter to achieve the best tracking performance is then presented. In addition, two theorems and one lemma which facilitate design of robust wavelet sliding-mode control are proved. Also, two simulation examples are presented to illustrate the performance and the advantages of the proposed method.