The main goal of this investigation is to establish modeling of a squeeze-mode magnetorheological (MR) damper and to design a semiactive fuzzy controller for vibration reduction. To model the MR damper, the Bouc–Wen model has been used in many past studies. However, using the Bouc–Wen model to characterize the squeeze-mode MR damper needs a lookup table of system parameters for the application with various amplitudes and frequencies. Therefore, a biviscosity model is proposed to describe this squeeze-mode MR damper. In addition, genetic-algorithm-based optimization is used to evaluate the parameters of the system. To reduce the vibration of the structure, a semiactive fuzzy controller using the MR damper is presented for the structure vibration at various frequencies. To check the consistency of the proposed fuzzy controller, the real-time implementation validated the performance of the controller.