Externally bonded composite systems have become an attractive alternative to conventional methods for strengthening and rehabilitating the built infrastructure, particularly as applied reinforced concrete (RC) or masonry structures. Such systems can be classified based on the matrix, where the established technology uses organic-based matrices, known as fiber reinforced polymer (FRPs) composite systems, and novel alternatives use inorganic-based matrices, referred to as fabric reinforced cementitious matrix (FRCM) composites. Both types of systems rely on the bond between the composite and the substrate to transfer stresses through the matrix to the fiber/fabric. Bond is of critical importance in flexural strengthening applications, where delamination failure occurs between the substrate and system due to loss of bond. Although numerous research studies have demonstrated the effectiveness of externally bonded systems, the long-term performance with regards to the durability of the system remains a key concern to be addressed, to fully embrace such structural rehabilitations solutions. The long-term study performance of composite systems under aggressive environments is partial and generally focused on mechanical properties only, where studies addressing the durability performance in terms of the tensile characteristics have shown that FRP systems exhibit a mechanical degradation, while FRCM systems remain relatively unchanged. However, evaluating the durability of the bond between the composite and substrate is a critical aspect, and limited information is available. To this end, this study experimentally evaluates the tensile and bond strength of different FRP and FRCM composite systems after aging in different environments and periods of exposure; including, 100 % relative humidity at 38°C, saltwater, and alkali solution (pH 9.5), representative of aggressive service environments.