The buck converter is widely utilized in various applications such as solar chargers, electrical vehicles and space exploration. The use of an efficient controller in buck converters reduces the heat and losses, extends the useful life, and allows for smaller gadgets to be built. In this research, a novel technique is proposed to regulate the output voltage of the buck converter. For this purpose, the mathematical model of the converter is introduced. Next, the adaptive sliding mode is suggested to regulate the output voltage. In order to ensure the faster transient response and finite-time convergence, the terminal sliding mode control is suggested. The singularity problem is solved by using nonsingular terminal sliding mode control. The switching gain is adaptively scheduled according to the fuzzy logic system. Finally, some simulation results including the parametric uncertainties, measurement noise, and steady-state error analysis are illustrated to demonstrate the efficiency of the proposed controller.