After about 80 years of introducing the Cockcroft–Walton (CW) circuit, it is still widely used because of its advantages, such as simplicity and high step-up gain. Several studies focused on the performance and design optimization of the circuit, but a dynamic model of the circuit remains to be established. This study analyzed the operation principles of an n-stage current-fed Cockcroft–Walton (CF-CWVM) during transient and steady-state operations. Then, an approach was derived to achieve a mathematical model for CF-CWVM with an arbitrary number of stages. A mathematical model for one- and two-stage CF-CWVM was developed, and its results were compared with simulation results. The theoretical model and simulations were validated by providing a prototype of CF-CWVM and comparing the results with the model outputs.