This paper presents a direct model predictive control method for DC-DC buck converters, designed to offer stable output voltage while simultaneously regulating inductor current. Utilizing only one control loop, this method simplifies the design and regulation process and enhances dynamic performance by avoiding additional loops such as PID controllers. The strategy supports both start-up and steady-state conditions, providing a soft start-up process and desired stable steady-state without extra procedures. Furthermore, the algorithm is suitable for buck converters operating in both continuous (CCM) and discontinuous conduction modes (DCM). The effectiveness of this approach is validated via simulation and experimental results.