Multifunctional materials are highly desirable not only for energy storage and conversion devices but also for integrated self-driven water-splitting systems. In this study, we propose a facile approach for developing a material with a CuCo₂O₄/MoNi core/shell structure that is encapsulated in an NiO nanolayer. Herein, the abundant active sites created by the porous hierarchical heterostructure and the corresponding nanointerfaces endowed the developed material with exceptional electrocatalytic activity. A supercapattery, consisting of an NiO@CuCo₂O₄/MoNi heterostructured cathode and an activated carbon anode, was effective for driving a water electrolyzer, which utilized the electrocatalytic heterostructure as a bifunctional material for both electrodes of the electrolyzer. This integrated supercapattery driven water splitting system was enabled by one electrocatalytic material. The results obtained herein suggest that both the supercapattery and electrolyzer outperform their previously reported counterparts. Further, the excellent performance suggests that the introduced approach can facilitate the design and development of inexpensive, but excellent multifunctional materials for diverse applications.