RuO2/activated carbon nanofiber (ACNF) composites containing graphene are prepared by a simple electrospinning method, followed by physical activated carbonation. We investigate the electrochemical properties as supercapacitor electrodes and the structural properties of these RuO2/ACNF materials as a function of the graphene concentration. The porous RuO2/ACNF composites exhibit an improved microstructure in terms of increased surface area, large mesopore volume fraction, and increased electrical conductivity with increasing graphene content. The RuO2/ACNFs with 3wt% graphene are characterized as having a large specific surface area of up to 1552.2m2g−1, mesopore volume fraction up to 53%, high electrical conductivity of over 0.59Scm−1, gravimetric capacitance of 180.2Fg−1 and energy density of 20.4–15.3Whkg−1 over a power density range of 400–10,000Wkg−1 in 6.0M KOH electrolyte. These results suggest that RuO2/ACNF with graphene offers the benefits of low resistance for charge diffusion and a short pathway for ion transportation. Therefore, RuO2/ACNF with graphene shows good capacitive behavior when applied as an electrode material for supercapacitors in terms of high rate capability, large capacitance, and more efficient energy density.