SummaryTo enhance the convergent rate and robustness of buck‐type DC‐DC converter system, a new finite‐time voltage regulation control algorithm is proposed in this paper. First, an average state space‐based model is analyzed, which considers both the parameters uncertainties and the variations of load and input voltage. By using saturation finite‐time control theory, at the first step, in the absence of disturbance, a new fast voltage regulation control algorithm is designed, which can guarantee that the output voltage converges to the reference voltage in a finite time. Because the saturation constraint is considered during the controller design, the duty ratio function of the converter satisfies the constraint between 0 and 1. Second, in the presence of disturbance, a finite‐time convergent disturbance observer is designed to estimate the unknown disturbances in a finite time. Finally, a disturbance observer‐based finite‐time voltage regulation control algorithm is developed. Compared with PI (Proportional‐Integral) control algorithm, circuit simulations show that the proposed algorithm has a faster regulation performance and stronger robustness performance on disturbance rejection.