Lamellar V5O12·6H2O nanobelts coupled with inert Zn(OH)2·0.5H2O are in situ fabricated via a facile hydrothermal strategy. Herein, the inert Zn(OH)2·0.5H2O phase acts as a buffer matrix to strengthen the structural stability of V5O12·6H2O host material, relieving the severe volume variation. Therefore, benefiting from the large interplanar spacing of active V5O12·6H2O and volume buffering effect of inert Zn(OH)2·0.5H2O, V5O12·6H2O/Zn(OH)2·0.5H2O hybrid (denoted as Z‐V5O12·6H2O) sustainably endures the repetitive Zn2+/Na+ insertion/extraction and boosts the electrochemical properties. As cathodes for aqueous zinc‐ion batteries, the Z‐V5O12·6H2O hybrid shows a high discharge capacity of 328 mAh g−1 at 50 mA g−1 and keeps 146 mAh g−1 at 1 A g−1 after 1000 cycles. For nonaqueous sodium‐ion batteries, the hybrid also furnishes a high initial discharge capacity of 241 mAh g−1 at a current density of 50 mA g−1 and maintains 97 mAh g−1 at 100 mA g−1 after 100 cycles.