The seismic vulnerability of unreinforced masonry (URM) structures and their extensive presence worldwide has driven significant efforts in the assessment and retrofit of existing buildings. Indeed, inherent weaknesses of masonry material and lack of adequate provisions to withstand horizontal actions often lead to delamination or local out-of-plane failure mechanisms. However, even after mitigating these issues and promoting a global three-dimensional behavior, the seismic performance under horizontal excitations might still remain inadequate. Consequently, common strengthening solutions involve jacketing through materials with significant tensile strength, such as fabric-reinforced cementitious matrices or composite-reinforced mortars, applied to one or both sides of the masonry walls, helping overcome the primary weakness of masonry: its low tensile capacity. This paper presents a novel three-dimensional equivalent-frame macroelement that effectively couples the in-plane and out-of-plane responses of strengthened masonry walls under lateral loads. The proposed model extends a pre-existing unstrengthened two-dimensional formulation, using a computationally efficient axial-flexural integration scheme to simulate the nonlinear static and dynamic behavior of URM panels with a limited number of degrees of freedom. Furthermore, taking advantage of the versatility of the proposed three-dimensional formulation, additional reinforcement is incorporated into the macroelement, enabling the explicit modeling of several strengthening solutions. The capability of the resulting macroelement formulation in reproducing lateral strength and stiffness, hysteretic cycles, and displacement capacity of masonry panels, is finally validated against experimental outcomes.