Abstract: O3-type layered oxides exhibit remarkable advantages in terms of high energy density and high operating voltage. However, as cycling progresses, their intricate phase transitions lead to contraction of the spatial structure and substantial volume changes. These changes impede the diffusion of Na⁺ and are likely to trigger a series of issues, including capacity fading and an increased interfacial impedance. In this study, compounding sodium superionic conductors with O3-type layered oxides to fabricate composite cathode materials is proposed as an effective optimization strategy. Accordingly, the sodium superionic conductor Na₃Zr₂Si₂PO₁₂ and the O3-type layered oxide Na(Ni_0.33Cu_0.06Fe_0.28Mn_0.33)_0.9Ti_0.1O₂ were synthesized and subsequently composited to fabricate a series of cathode materials. Na₃Zr₂Si₂PO₁₂ was used to enhance ionic conductivity, reduce interfacial impedance, and replenish highly desodiated Na⁺. The composite cathode Na(Ni_0.33Cu_0.06Fe_0.28Mn_0.33)_0.9Ti_0.1O₂-5% Na₃Zr₂Si₂PO₁₂ exhibited outstanding electrochemical performance. It delivered discharge-specific capacities of 123.0 mAh/g and 110.6 mAh/g at 0.5 C and 1 C, respectively, with capacity retentions of 68.9% and 65.8% after 100 cycles.