The robust tracking control of R¨ossler system with external uncertainties is investigated. Based on dynamic surface control, a robust controller is designed and the update laws of the unknown parameters are given, under which all the signals of the closed-loop controlled system can be semi-globally ultimately bounded, influence of the uncertainties can be attenuated effectively, and the output trajectory of the chaotic system can approach any desired orbit with an arbitrarily small error bound without knowing the upper bounds of the unknown parameters and external uncertainties. Theoretical analysis is derived as well based on Lyapunov stability theory. Finally, numerical simulations are given to verify the effectiveness and robustness of the proposed control scheme.