A high-rate, coin cell (CR2023) supercapacitor (SC) with excellent charge storage performances was fabricated using hydrophilic poly(aniline-co-p-phenylenediamine) nanofiber-decorated nitrogen-doped reduced graphene oxide (referred to as P(ANi-co-pPDA)@N-rGO) as a redox electrode material and 25 mM Fe(CN)6 4+/Fe(CN)6 3+ in 1 M H2SO4 as a redox-active electrolyte. P(ANi-co-pPDA)@N-rGOs were synthesized by co-electropolymerization using different co-monomer feeding ratios in 0.5 M H2SO4. From electrochemical measurements, P(ANi-co-pPDA)@N-rGO) with 4% pPDA ratio (noted as S-2@N-rGO) showed a high specific capacity of 350 Cg−1 (413 Cg−1 at 10 mV/s), which was 2.2 and 4.5 times as high as those of PANi@N-rGO and N-rGO, respectively. Moreover, S-2@N-rGO exhibited an improved specific energy of 35.4 Whkg−1 with a specific power of 969 Wkg−1 at 0.5 Ag−1, a good capacity retention of 85% after 1000 cycles at 6 Ag−1 and a low equivalent series resistance of 2.83 Ω. The excellent SC performances can be attributed to its high electrical conductivity, highly hydrophilic nature and excellent electrochemical properties leading to a synergistic effect between co-polymer/N-rGO electrodes and Fe(CN)6 4+/Fe(CN)6 3+ redox electrolytes. Thus, the P(ANi-co-pPDA)@N-rGO) SCs produced by the simple cyclic-co-electropolymerization method were highly potential for advanced energy storage applications.