Exploiting chemical sensors (CSs) with high-activity sensitive materials is very important for the detection of volatile organic compounds (VOCs). Co-containing spinel oxides are potential candidates for sensing layers. However, the intrinsic activity always hinders their further progress of sensing performances such as sensitivity and selectivity. Here, a facile strategy is successfully developed for the substitution of Co cations into Zn cations in Co₃O₄ without sacrificing multi-shelled hollow structure. The synthesized cabbage-shaped ZnCo₂O₄ exhibited the enhanced formaldehyde sensing capability compared to the Co₃O₄counterpart. The sensitivity to 100 ppm formaldehyde for ZnCo₂O₄-sensors is 7.4 at 180 °C, which is 6.2 times higher than that of Co₃O₄-sensors. In addition, the ZnCo₂O₄-sensors also show the fast response/recovery time (9/12 s) compared to Co₃O₄-sensors (55/63 s). Interestingly, Zn²⁺ introduction can facilitate the accumulation of holes and generate more defective oxygen and adsorbed oxygen effectively. Consequently, remarkably improved sensitivity, selectively and fast response/recovery process are demonstrated for the ZnCo₂O₄-based sensors. The results offer crucial insights in realization of highly sensitive spinel oxide materials for CSs.