The influence of environmental aging on the durability of the civil structural components made of fiber/epoxy composites is a big concern for many industries nowadays. For that reason, accelerated environmental aging was performed on the bolted joints prepared from carbon/epoxy composites. The bolted joints were designed using ASTM D 5961 having an edge to diameter ratio and width to diameter ratio as 5 and 6, respectively. The cyclic exposure of ultraviolet radiation for 8 h at 60 °C and condensation for 4 h at 50 °C was used under accelerated environmental aging conditions according to ASTM G154 standard for 0, 250, 500, 750 and 1000 h. It was found that at shorter durations, the positive effect occurred with increased strength, whereas the strength decreased for longer durations. The failure loads were found for neat and multi-walled carbon nanotube (MWCNT) added composite bolted joints for unaged and aged conditions at varying bolt preloads. The MWCNT added composites shows better results than neat composites. It was also observed that bolt preloads improved the load-bearing capacity for MWCNT added composite joints even after 1000 h of accelerated aging.