Achieving a novel structural construction and adopting appropriate catalyst materials are key to overcoming inherent limitations of gas sensors in terms of designing sensing layers. This work introduces NiO/NiCo₂O₄ truncated nanocages functionalized with PdO nanoparticles, which were proved to possess the ability of effective acetone detection. The device realized an enhanced acetone-sensing sensitivity, together with excellent selectivity and long-term stability. The sensing performance is far better than sensors based on NiO/NiCo₂O₄ solid nanocubes and NiO/NiCo₂O₄ truncated nanocages without PdO decorating, which is related to cooperative effects of the high specific surface area and efficient catalytic activity. The results provide promising metal–organic frameworks (MOFs)-derived material with the optimization of catalytic performance, demonstrating the remarkable potential for acetone sensors.