Abstract: The tower of the wind turbine is in a state of vibration due to the wind loads and the rotation of the rotor, which causes bolt loosening and flange fatigue failure. One method to reduce the wind-induced vibration of the wind turbine tower is to install a Tuned Mass Damper (TMD). However, a unidirectional TMD cannot reduce vibrations in different directions, and installing multiple dampers would increase the load to the turbine tower, raise costs, and affect internal accessibility. A novel horizontal omnidirectional TMD is proposed to reduce the vibration of the turbine tower in various directions using only a single mass block. Taking a wind turbine tower as the research target, the ANSYS Workbench finite element simulation platform is adopted to analyze the wind-induced vibration of the wind turbine tower model. The horizontal omnidirectional TMD is designed and installed inside the tower, and its vibration reduction performance under fluctuating wind is investigated. The results indicate that a TMD with a mass ratio of 0.02 exhibits optimal control effects on the maximum displacement and maximum stress of the tower, resulting in a 19.4% reduction in the maximum displacement at the tower top, a 34.8% decrease in the displacement standard deviation, a 21.3% decrease in the maximum stress at the tower base, and a 33.9% reduction in the stress standard deviation. The novel horizontal omnidirectional TMD demonstrates good control performance against tower vibrations caused by winds from different directions, achieving a vibration reduction efficiency range of 34.8% to 56.8% for displacement and 33.9% to 57.8% for stress under cut-out wind speed conditions.