The recent research is trending to develop robust solutions for controlling nonlinear systems with uncertain dynamics. This paper employs a novel approach of active disturbance rejection control (ADRC) based on extended state observer (ESO) to solve the nonlinear control problem with uncertain dynamics. To evaluate the actual performance of the ADRC, the classical nonlinear system of cargo ship steering is studied. The ADRC actively estimates and compensates for internal dynamic uncertainties and external disturbances. In the case of ship steering, the variations are mainly wind and wave disturbances. Simulation results show the excellent performance of the ADRC for cargo ship steering in terms of ship trajectory tracking, disturbance rejection, noise tolerance, and robustness to uncertainties with the well-tuned controller and estimator bandwidths. © 2015 American Automatic Control Council.