Many DC/DC converters with voltage boosting functions have zeros on the right half of the complex plane; they are non-minimum phase systems. Conventional linear controllers have trouble obtaining the ideal control quality of simultaneously satisfying the performance requirements with respect to stability, speed, accuracy, robustness, and simplicity. This paper combines a proportional integral (PI) control rule with an adaptive parameter-adjusting circuit composed of memristors and adaptively adjusts the controller parameters through a memristor circuit to adapt to changes in system operation. The parameter update rules of voltage- and current-controlled memristors are discussed. The analysis indicates that under the control of the memristor-based adaptive PI controller, the closed-loop system's output deviation continuously decreases along the gradient and approaches a minimum. Simulations and experimental verification are performed using a boost converter as the controlled object. The results show that, compared with a conventional PI controller, the proposed controller is more robust, and it is suitable for controlling a power electronic system with nonlinearly time-varying uncertainty and disturbance.