<p>Na₃V₂(PO₄)₂F₃ (NVPF) has garnered significant interest as a cathode material for sodium-ion batteries (SIBs) because of its outstanding thermal stability, high operating voltage (~ 3.9&#xa0;V vs. Na⁺/Na), and 3D open framework structure. However, NVPF has inherently low electronic conductivity and is prone to volume changes during charging and discharging. To address the above issues, this study proposes a co-oxidation strategy for preparing a GN/CNT composite 3D conductive network, which is then combined with NVPF nanoparticles to construct a co-oxidized GN/CNT-coated NVPF (NVPF@O-GN/CNT) hierarchical structure. This strategy simultaneously regulates the surface functional groups of CNT and GN through chemical oxidation, enhancing the chemical bond interaction between the two and forming a stable 3D interconnected conductive network. The network can significantly improve the efficiency of electron/ion transport and reduce volumetric strain throughout the charging and discharging process; the flexible lamellar structure of GN and the directional conductivity of CNT work together to further reinforce the electrode’s structural stability. Moreover, the uniform loading of NVPF nanoparticles in the O-GN/CNT conductive network can shorten the diffusion path of Na⁺ and enhance the reaction kinetics. The battery’s electrochemical performance was greatly enhanced by the NVPF@O-GN/CNT electrode, attaining a specific capacity of 116.7 mAh g⁻¹ at 20 C and a high discharge specific capacity of 126.6 mAh g⁻¹ at 1 C. After 5000 cycles at 20 C, the capacity retention rate increased to 82.69% (96.5 mAh g⁻¹), offering a workable method for creating inexpensive, long-lasting, high-performing sodium-ion battery cathode materials.</p>