In this study, the fatigue behavior of graphene nanoplatelets (GnPs) reinforced and non-reinforced basalt/epoxy composite pressure vessels (B-CPVs) with [±55°]4 configurations under alternating internal pressure was experimentally investigated according to ASTM D2992. Fatigue tests of GnPs reinforced and unreinforced B-CPVs were performed using a close-ended test apparatus over basalt/epoxy composite pipes. The fatigue test of the specimens was carried out at 25 cycles/min (0.42 Hz) and 0.05 stress ratio (R). The tests were conducted at load rates of 30%, 35%, 40%, 50%, and 60% of the ultimate hoop stress (σHS) where weepage damage occurred in the CPVs. The formation and order of the damage were determined by observing damages generated during the fatigue tests. These damages resulted in weepage, leakage, and burst (final failure). It was detected that the fatigue cycle number of all observed damages rises with the addition of a low content (0.25 wt%) of GnPs and improves the fatigue life of the basalt/epoxy CPVs. In addition, the effect of GnPs on fatigue behavior was offered and discussed through S–N curves.