Research on the impact behaviour of concrete masonry unit (CMU) walls strengthened with fiber-reinforced polymer (FRP) composites is considerably limited. In this study, the effectiveness of externally bonded (EB) FRP technique on the resistance of CMU walls under high-velocity impact force was therefore investigated numerically. Finite element (FE) models were developed using LS-DYNA. The Concrete Damage Rel3 model and Enhanced Composite Damage material models were used for concrete and composite materials, respectively. Furthermore, the Add Erosion and Smooth Particle Hydrodynamics options were included to accurately represent impact behaviour. The FE models were validated using literature results. Applications of various EB FRP composites to CMU walls were investigated with the parameters of fiber types, fiber direction, fiber layer, and impactor velocity. The numerical results show that the EB FRP strengthening technique is significantly effective to improve the impact resistance of CMU walls by preventing an impactor from perforating the CMU walls.