Vanadate oxides with low price and high theoretical capacity are competitive cathodes for aqueous zinc-ion batteries (AZIBs). However, the existing problems such as sluggish Zn2+ ion mobility, weak conductivity, and complicated flexible electrode preparation hinder the development of their practical applications in flexible AZIBs (FAZIBs). Herein, sodium-ion and polyaniline are co-inserted into ammonium vanadate (NaNVO-PANI) nanoarrays, which can serve as the novel freestanding cathodes for FAZIBs. By virtue of synergistic pillar effect of sodium ions and polyaniline, the interplanar spacing of NaNVO-PANI expands to ≈13.8 Å. Both experimental data and theoretical calculation confirm that the optimal spacing of NaNVO-PANI can boost enhance the electronic conductivity and reduce Zn2+ diffusion barrier. As expected, the resulting coin-type AZIBs exhibit high capacity of 610.7 mAh g−1 at 0.5 A g−1 and remarkable capacity retention of 98% after 5000 cycles at 5 A g−1. More encouragingly, quasi-solid-state FAZIBs with sandwich structure are assembled, achieving impressive energy density of 345.59 Wh kg−1 at a power density of 380.46 W kg−1. This study is of great significance for developing high-performance vanadium-based electrode for wearable FAZIBs.