Abstract: A novel high-damping mooring system is proposed to enhance the stability and reduce the structural responses of floating platforms in offshore renewable energy applications subjected to wave forces. In this system, the mooring cable is linked to the platform via a rotatable rigid arm, with the arm's rotation restricted by a spring and a damper in parallel and positioned between the arm and the platform. Simplified and dynamic models of the proposed mooring system are presented, respectively, for damping evaluation and coupled numerical analysis. The OC3-Hywind spar is selected for performance evaluation and optimization of the high-damping mooring system. The damping ratio of the platform is obtained and maximized through complex modal analysis. The results show that a maximum of 11.4% additional damping ratio can be attained for the platform surge and sway motions with implementable configuration of the mooring. Coupled analyses of the platform under irregular waves further show that the standard deviation of platform displacements can be reduced by up to 40% and cable dynamic tensions can be reduced by approximately up to 30%.