Precisely tuning the catalytic species in bifunctional electrocatalysts is vital for achieving highly efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) processes, but remains a significant challenge. Herein, a highly active electrocatalyst composed of NiCoB/CuFe−LDH (NCCF) was developed by interface engineering for overall water splitting applications. The outstanding electrocatalytic activity is attributed to the interfacial synergistic effect of the corresponding catalytic species on the NCCF heterostructure. As expected, the NCCF presented impressive HER activity with an overpotential of only 129.1 mV and delivered good OER activity with an overpotential of 235.6 mV at 10 mA cm−2 in 1 M KOH. Additionally, a two-electrode symmetric electrolyzer cell constructed with the NCCF heterostructure demonstrated efficient overall water splitting, achieving a low cell voltage of 1.66 V at 10 mA cm−2. Further, Density functional theory investigation demonstrates that the heterostructure exhibits enhanced electronic conductivity, which benefits its electrocatalytic activity. Over all investigation highlighting its potential for further advancement and optimization in renewable energy conversion technologies. © 2025 Elsevier B.V., All rights reserved.