Semiactive vibration control systems possess both the simplicity and inherent reliability of passive systems while maintaining the adaptability of active vibration control systems integrated with an appropriate control algorithm. One of the recent and promising technologies in semiactive vibration control is to utilize magnetorheological (MR) fluids (MRFs) and MR elastomers (MREs). The well-known remarkable feature of MR materials is the continuous controllability of stiffness and damping properties under external magnetic field. The unique controllable characteristic of MR materials has catalyzed comprehensive research and development focusing on vibration control systems including vehicle dampers, engine mounts, adaptive tuned vibration absorber, and seismic bearings. The major goal of this special issue is to provide recent research in applications utilizing MR materials. In particular, the special issue focuses on the MR techniques that deal with configuration design, dynamic modeling, and semiactive controller implementation along with simulation or/and experimental works. Therefore, the papers published in this special issue will be innovative references for the development of more advanced application devices or systems utilizing MR materials.