Due to the growing interest in three-dimensional (3D) printed soft actuators, the establishment of an appropriate mathematical model that could effectively predict the actuators’ dynamic behavior has become necessary. This study presents the development of an effective modeling strategy for the dynamic analysis of a 3D printed polyelectrolyte actuator undergoing large bending deformations. The proposed model is composed of two parts, namely electrical and mechanical dynamic models. The electrical model describes the actuator as a gray box model, whereas the mechanical model relates the stored charges to the bending displacement through considering the printed actuator as a discretized system connected by spring–damping elements. The experimental results verified the accuracy of the proposed model, particularly under large voltages and actuation bending. The proposed discrete rigid elements modeling strategy can be simply extended to other 3D printed hydrogel actuator systems where mechanical pixels are characterized by 3D printing.