Structural vibration is one of the main engineering concerns in recent decades especially in offshore structures due to the dynamic environment and accessibility. Among different methods, applying a device within the primary system for mitigating the vibration through system damping increment is one of the most promising methods. In this study, a combined novel Magneto-Rheological Tuned Liquid Column Gas Damper (MR-TLCGD) as a damping system is introduced for the first time in structural control field and the efficiency of the system is investigated on a three dimensional fixed offshore jacket platform under both wave and earthquake excitation. The performance of the system is studied through considering different values of yield stress and gas pressure as of the main parameters of MR fluid and gas damper. The results are compared to a previously studied Tuned Liquid Column Gas Damper (TLCGD) system. Based on the results, utilizing an MR-TLCGD system in an offshore structure can be defined as a proper choice for reducing structural vibration. It can be concluded that considering an appropriate value for yield stress and gas pressure, regardless of the results limitation for this case study, is of great importance in practical cases.