Carbon nanofiber is a well-known carbon nanostructure employed in flexible supercapacitor electrode. Despite recent developments, improvement in the performance of carbon nanofiber-based electrode is still the subject of intense research. We investigated the supercapacitor performance of porosity-induced carbon nanofibers (CNFs). The fabrication process involves electrospinning, calcination, and subsequent etching. The porous CNF not only delivers a higher capacitance of 248 F/g at a current density of 1 A/g, but also exhibits a higher rate performance of 73.54%, lower charge transfer resistance and only 1.1% capacitance loss after 2000 charge-discharge cycles, compared to pristine CNF. The excellent electrochemical behavior of porous CNF is correlated with the degree of graphitization, a higher volume of mesopores, and enhanced surface area. The as-fabricated symmetric device comprising porous CNF exhibits an energy density of 9.9Wh/kg, the power density of 0.69 kW/kg and capacitance retention of 89% after 5000 charge-discharge cycles. The introduction of porosity in CNFs is a promising strategy to achieve high-performance supercapacitor electrode.