Rechargeable sodium-ion batteries (SIBs) have attracted great attention as potential application in grid energy storage but are plagued by lacks of promising cathode materials with both excellent cycling stability and rate capability. Herein A novel ternary NASICON Na_3.8MnV_0.8Zr_0.2(PO₄)₃ is fabricated and tested as a cathode material. By Partial substitution with Zr⁴⁺, the obtained Na_3.8MnV_0.8Zr_0.2(PO₄)₃, delivering a capacity retention of 83.5% after 1000 cycles at 2 C, and an impressive rate capacity of 73.1 mAh g⁻¹ at 20 C and 66.8 mAh g⁻¹ at 60 C. Electron microscopy, x-ray diffraction, cyclic voltammetry, and first principle calculations show that this superior rate capability can be attributed to the broadened Na-ion channels and high Na-ion diffusivity. Furthermore, the volume expansion upon Na-ion de-insertion is lower than other NASICON materials (only 4.9%), which facilitates the structural integrity over cycling. This work paves the way in producing greener, high-power and long-life Na-ion batteries.