This paper presents a robust controller for a STATCOM device with saturated inputs. As the primary assumption, the proposed design considers the presence of unknown but bounded external perturbations and parametric variations. This proposal has a cascade structure, where a saturated super twisting control algorithm closes the currents control loop, and a high-gain proportional-integral (PI) algorithm ensures the voltage regulation. Thus, the exposed scheme provides an adequate performance of the STATCOM, considering the saturation of the inputs with the anti-windup feature. Posteriorly, a proper stability analysis presents the conditions for the appropriate operation of the closed-loop system in saturation and non-saturation regimes. Numerical simulations are also included to show the performance of the proposed controller.