Currently, low intrinsic conductivity seriously affects the development and large-scale application of Na3V2(PO4)3 (NVP). Herein, the binary K+/Mn2+ co-substituted Na2.96+xK0.04 V2-xMnx(PO4)3 (x = 0.005, 0, 0.01, 0.04) with enwrapped carbon nanotubes (CNTs) are synthesised. The incorporation of CNTs can form an effective conductive framework and provide more conductive paths, thus reducing the resistance of electron and ion migration thereby increasing the overall conductivity. Notably, replacing Na+ by pillar ion K+ with a larger radius can effectively strengthen the crystal structure of NVP, thus increasing the cycling stability of the battery. Besides, due to the differences in atomic radius and electronic structure between Mn2+ and V3+, this substitution can change the local environment of Na+ in the crystal, thus affecting its migration behaviour. Because of the larger ionic radius of Mn2+, it helps to increase the inter-facial distance in the crystal structure, which is favourable to promote the migration of Na+. Meanwhile, divalent Mn2+ occupying V3+ site can generate p-type doping effects, which introduces more hole carriers, thus increasing the intrinsic conductivity of the material. Accordingly, the optimized NVP/C@KMn0.01 achieves a capacity of 106.4 mAh g−1 at 1C, and maintains 98.1 mAh g−1 with a retention rate of 92.19 % after 230 cycles. At 15C, it reveals 106.1 mAh g−1 and keeps 82.5 mAh g−1 after 5800 cycles, corresponding to a capacity retention of 77.76 %. Furthermore, NVP/C@KMn0.01//CHC full cell delivers a high value of 155.0 mAh g−1 and enables to lighten the LED bulbs, indicating its excellent practical application prospects. The improved crystal structure of NVP/C@KMn0.01 is further verified by post-cycled XRD/SEM/XPS measurements.