This paper discusses the effectiveness of Composite Reinforced Mortars (CRM) and Fiber-Reinforced Mortars (FRM) as seismic retrofit of existing stone masonry buildings. A large experimental campaign was conducted within the ERIES-RESTORING project, involving vertical compression, diagonal compression, and quasi-static cyclic tests. Undressed stone masonry specimens under different retrofit configurations, compatible with historical masonry, were studied: bare masonry, CRM applied on one side, CRM applied on two sides, and FRM applied on two sides. The CRM retrofit consisted of a glass-FRP mesh embedded in natural hydraulic-lime mortar and the FRM retrofit of a mortar with polymeric fibers. For the vertical and compression tests, three masonry wallettes were tested for each retrofit configuration, excluding the FRM that was not tested under this type of loading. Instead, for the testing of the in-plane cyclic behavior, full-size piers were subjected to a constant axial stress level and double-fixed boundary conditions. Two different pier aspect ratios were investigated to study the flexural and shear behavior. The FRM retrofit was tested only under quasi-static cyclic shear-compression loading and was applied directly to both sides of a single pier with an aspect ratio inducing flexural behavior. The experimental results, including damage mechanisms, lateral strength, and deformation capacity, can be referred to for calibrating advanced numerical models and conducting parametric studies on geometric, material, and loading conditions. Lastly, the outcomes of this project will contribute to the validation of analytical models and the development of design guidelines and code requirements for these retrofitting techniques on historical masonry.