Composite materials, particularly glass fibre-reinforced polymers, or GFRP are being used far more frequently. Airframes have been manufactured utilizing reinforced composites, including struts, frames, and flaps, employing raised epoxy-based co-cure technology. The current research describes a multi-scale approach to fortifying graphene nanoparticles (GNP) and carbon fibre Z-pins in order to strengthen the flat-joggle-flat composite joints with different manufacturing technique. Shear investigation showed that by adding GNPs and putting carbon fibre pins (Z-pins) in a crosswise position (perpendicular to the plane) to the joint's surface, concurrent reinforcement gives rise to greater shear characteristics with quasi-static loads. Specifically, there was a 45.6% improvement in shear resistance when contrasted with unreinforced co-cured FJF joints. The FESEM has been utilized to demonstrate the failure analysis of the specimens, which shows the clear failure mechanism of the FJF joint specimens. The FJF joint with multiscale reinforcement has a very high natural frequency of 685.1 Hz as compared to other configurations, according to the vibration analysis. © 2024 Elsevier B.V., All rights reserved.