Ankle inversion injuries are prevalent among athletes and the general population, causing significant pain and mobility issues. This paper presents the design and evaluation of an ankle-foot orthosis (AFO) to prevent and mitigate the effects of ankle inversion injuries. A detailed CAD model of the AFO was developed, followed by simulations using OpenSim software to assess its performance. Various parameters, including muscle strain and subtalar joint angle, were analyzed under different simulated conditions to determine the optimal AFO material stiffness. The results suggest that the AFO significantly reduces muscle strain and improves joint stability, offering valuable insights for ankle injury prevention and rehabilitation.