The exploration of high-performance trifunctional electrocatalysts for the oxygen reduction reaction (ORR), the oxygen evolution reaction (OER), and the hydrogen evolution reaction (HER) is quite critical for the development of sustainable energy technologies. Herein, a facile template-engaged approach is developed to synthesize porous RuO₂-Co₃O₄/C (RuCoO/C) nanocubes as advanced trifunctional electrocatalysts. Benefiting from the compositional and structural features, the as-synthesized RuCoO/C nanocubes exhibit high half-wave potential toward the ORR (E_1/2@0.83 V) and small overpotentials for the OER (223 mV@10 mA cm⁻²) and the HER (49 mV@10 mA cm⁻²), as well as good stability for the ORR/OER/HER. When evaluated in rechargeable zinc–air batteries (ZABs) and water electrolysis cells, the RuCoO/C nanocubes demonstrate both high efficiency and splendid stability. As a proof of concept, an integrated system is established to achieve the production of H₂ by ZAB-powered overall water splitting.