This paper evaluates the shear strength of masonry wall panels reinforced with FRP composite systems under out-of-plane loading conditions. An analytical model and experimental study were developed to predict the out-of-plane shear strength of the FRP reinforced masonry walls. The experimental study was performed on eighteen 1000×600×200 mm walls reinforced with FRP on one side while the model is based on the theories of elasticity and fracture mechanics. The presented study accounts for the shear contribution of the masonry units and the fiber overlays. The experimental program presented in this paper is used for validation of the analytical model. A parametric study is performed to evaluate the shear strength of the walls for various geometric properties of the fiber reinforcement. It was found that the shear strength of the retrofitted system is a function of the thickness of the FRP system used. As a result of this investigation, guidelines for selecting the thickness of the FRP retrofitting systems can be determined for any required shear strength.