Given that the DC-DC buck converter (DDBC) is an example of a nonlinear system, and also considering the disturbance and changes related to its parameters, the output voltage control in this DDBC will face several challenges. In this paper, a PD-PI cascaded controller is designed to control the voltage in the DC-DC buck converter. In this cascaded controller, the PD controller, as the outer loop controller, is responsible for responding quickly to voltage changes and damping them, and the PI controller is responsible for eliminating the error caused by voltage changes. Considering that the accurate and optimal adjustment of the parameters related to the cascaded controller is crucial to its performance, the Grey Wolf Optimizer algorithm has been employed to optimize these parameters. This algorithm offers several advantages, including intelligent search, parameter fine-tuning, and stable and rapid convergence. To assess the robustness of the proposed PD-PI(Grey Wolf Optimizer) approach against disturbances and parameter variations, multiple scenarios were developed and its performance compared with that of control strategies like PD-PI (Electric Eel Foraging Optimizer) and PD-PI (Flood algorithm). According to the results, the proposed method outperforms other control methods in terms of various criteria, including Settling time, Rise time, Peak time, Overshoot, and Steady state error.