This chapter is devoted to the generalized proportional integral (GPI) observer-based active disturbance rejection control (ADRC) approach for trajectory tracking in induction motors subject to, both, external disturbance inputs and endogenous nonlinearities treated also as unknown disturbances. The first section of the chapter deals with the problem of controlling induction motors using two observer-based ADRC loops, one for the current tracking task and a second one for the angular velocity regulation. The second section presents the armature voltage field-oriented controller for the decoupled regulation of the angular velocity and the flux magnitude. Both schemes present experimental results and comparisons with existing control strategies. Finally, the appendix contains some theoretical generalities about the ADR scheme and its relation to global ultra-models.