In this paper, a Lyapunov-based model reference proportional-integrated-derivative (PID) is designed using this approach for a DC / DC Buck converter. However, under a wider range of disturbances, the PID strategy is not suitable for practical applications, and the parameters must be tuned again for more reliable operations. To this end, a Lyapunov definition-based adaptive mechanism is adopted for the PID strategy, which can increase the stability and robustness of this scheme under various disturbances. Moreover, the system is considered a black-box without the need for accurate mathematical modeling of the system that can result in a lower computational burden as well as ease of implementation. The Lyapunov concept is a modern adaptive algorithm that can find optimal answers in shorter periods with more accuracy and reliable stability insurance. To examine the strength of this method, conventional fractional-order PID (FOPID) and PID control techniques are also tested to be compared with this work using the PSO algorithm to tune their parameters. Finally, the results related to both simulations and experimental outputs are tested, showing faster dynamics and significant robustness of Lyapunov-based PID strategy in different challenging scenarios.