Recent developments in geometrical linearization techniques cannot be directly applied to nonlinear chemical processes, such as those with unstable zeros. This paper deals with the problem of designing a robust tracking controller for uncertain nonlinear systems with a nonminimum phase. With the approximate linearization and parametric transformation algorithms, the actual output can converge to the desired trajectory with an arbitrary degree of accuracy. When the bounds of "lumped" uncertainties can be available, with the use of the easily estimating and feasible tuning scheme the overall system stability can be guaranteed. Inspired by the model-based control strategy, we introduce a minimum-phase, approximate model as an open-loop observer such that the observer-based controller has stable inverse and the asymptotic output regulation for uncertain, nonminimum-phase systems can be achieved. Finally, in the illustrative example, an adiabatic stirred-tank reactor using the Van de Vusse reaction, the present methodologies are verified, obtaining the expected results.