Zinc oxide (ZnO)-based porous carbon composite nanofibers (ZnO–CCNFs) are prepared by one-step electrospinning and subsequent thermal treatment using zinc acetate, as the pore generator and ZnO precursor. In particular, the PAN-based nanofiber paper contains in-frame incorporated nitrogen surface functionalities, due to its large residual nitrogen content in the char. The N functionalities doped at the graphite edges enhances their capacitance by the pseudocapacitive effect. Therefore, the ZnO–CCNFs showed higher capacitance (163Fg−1 at 1mAcm−2) and energy density (20.80–14.80Whkg−1 in the power density range of 400–20,000Wkg−1) than the control sample of carbon nanofibers (CNFs) in aqueous electrolyte. The combination of the high surface area of CNFs with the large capacity of surface functional groups such as N, O, and ZnO as the faradic electrode material affords the advantages of both the double layer capacitance and the pseudocapacitance, thereby offering potential applications for supercapacitors.