Na3V2(PO4)3 (NVP) has been applied to be suitable candidate due to its stable structure and high capacity. However, the poor conductivity limits its further application. Herein, we propose a simultaneous modification strategy to optimize the crystal structure and morphological features. The K+ substitution results in a pillar effect to support the crystal structure and expand the channels for Na+ migration. The replacement of V3+ by Co2+ is facilitated to generate hole carriers to improve the internal electronic conduction. Moreover, recombination with lamellar rGO is favorable to reduce the particle size of grains, offering shortened pathways for electronic transportation. Besides, the carbon layer and conductive rGO construct an efficient network for accelerated electronic transportation. Comprehensively, the K0.1Na2.95V1.95Co0.05(PO4)3@rGO (KC005@rGO) delivers a capacity of 120.6 mAh g−1 at 0.1C. It releases a capacity of 102.78 mAh g−1 and maintains 94.75 mAh g−1 after 600 cycles at 5C. Even at 20 and 50C, it shows an initial capacity of 98.6 and 90.36 mAh g−1 and remains 68.9 and 56.8 mAh g−1 after 1000 cycles. Furthermore, the asymmetric full cell of KC005@rGO//Bi2Se3 presents a capacity of 168.4 mAh g−1 with an energy density of 455.49 Wh Kg−1, demonstrating its great practical application.