In this paper, a suitable and high-performance electrode material for practical applications was developed using a simple two-step approach. Here, we report that nitrogen-doped graphene quantum dots with co-doped polyaniline (N-GQDs-PANI) were fabricated by in situ polymerization as supercapacitor electrodes and that the effect of the amount of N-GQDs in the electrode material on the electrochemical performance was investigated. The integration of N-GQDs into co-doped PANI structure prevented the agglomeration of PANI and enabled the fabrication of N-GQDs as thin film on the surface. This modification improved the charge transfer of the N-GQDs-PANI electrode compared to N-GQDs and pure PANI electrodes, allowing it to exhibit superior electrochemical performance. The N-GQDs-PANI electrode has a specific capacitance of 503 F/g at a current density of 5 A/g with a capacitance retention of about 91.9 % after 10000 charge/discharge cycles.