<p>All-solid-state sodium-ion batteries (ASSSIBs) that applied inorganic solid electrolytes offer enhanced safety and stand out as promising contenders for the next-generation energy storage systems. Herein, an oxygen-incorporated Na₂ZrCl₆ (NZC) composite electrolyte with high ionic conductivity (1.52 × 10^‒4&#xa0;S·cm^‒1) at an ambient temperature was reported. The composite electrolyte, which was prepared through a mechanochemical reaction and formed a highly ionic conductive interface, consists of oxide between ZrO₂ and NZC. A series of characterization confirmed that oxygen interacted with sodium ions, resulting in enhanced Na⁺ diffusivity at the interface. The ASSSIBs, which comprise a NaNi_1/3Fe_1/3Mn_1/3O₂ cathode, a Na₁₅Sn₄ anode, and a Na₃PS₄ anodic interlayer with ZrO₂-NZC electrolyte, demonstrate a high discharged capacity of 104.9&#xa0;mAh·g^‒1, and significantly outstrip the baseline NZC electrolyte. This work offers an idea of methods for improving ion migration in halide solid electrolytes for practical feasibility in all-solid-state batteries.</p> Graphical abstract <p></p>