The application of sodium-ion batteries (SIBs) is largely depended on the high energy density electrode system since it suffers from intrinsic high voltage of Na (0.33V vs. Li). To overcome these limitations, we propose a high-voltage sodium-ion full cell via cathodic polarization suppression. NASICON structured Na3V2(PO4)3 (NVP) cathode and poorly-graphitized hard carbon (HC) anode are synthesized as the targeted materials through an easily scalable coprecipitation method and a simple biomass-directed technique, respectively. Through morphologic optimization and carbon decoration, the NVP half cell demonstrates a high output voltage of 3.4V, ultralong cyclability (over 4000 cycles) and distinguished rate capability (77mAhg−1 at 150C), which is attributed to the enhanced electrical transport behaviors and carrier transmission dynamics. When extended to NVP//HC, the overpotential has been successfully restrained, and the full cell exhibits a theoretical average voltage of 3.3V, which shows substantial increases in the energy density (>20%) compared to bulk and bare NVP based full cell. The prototype design of high-energy and low-cost sodium-ion full cell in this work opens the door for accelerating the development and application of SIBs.