<p>In historic stone masonry buildings, strong ground motions typically result in out-of-plane failure of the walls before their in-plane strength is reached. This phenomenon is especially pronounced in structures characterized by long unsupported spans perpendicular to their plane, in the absence of a diaphragm effect. In such cases, the strengthening intervention for the historic façade should be selected by considering the principles of conservation. The present study investigates the effectiveness of an innovative reinforcing configuration that builds upon the steel-cord-based techniques available in the literature, using experimental and numerical methods. The applied strengthening consists of no-tensioned steel cords embedded in the bed joints and vertically in both the head joints and the stone bricks of the masonry wall. A large-scale stone masonry wall specimen was designed and constructed to reflect the results of on-site material and dynamic tests performed on a reference historic masonry structure. A series of dynamic and quasi-static cyclic tests was conducted on both the unreinforced and reinforced conditions of the specimen. The proposed method was found to restore the out-of-plane strength without significantly increasing the stiffness of the damaged specimen. Furthermore, it was observed to improve the out-of-plane deformation capacity and overall structural integrity. The finite element models were calibrated based on the test data and exhibited a noteworthy agreement with the experimental results, particularly in terms of load–drift response and damage observations. Some model parameters were also proposed.</p>