Rational design and fabrication of electrocatalysts with outstanding performances and long-term durabilities are highly challenging for overall water-splitting reactions. Herein, interfacially engineered CoS@NiV-LDH heterostructures are fabricated by a simple top-down approach and used as bifunctional electrocatalysts for overall water splitting. Experimental results proved that the creation of an interface between pristine CoS and NiV-LDH can optimize the electronic structure of the active sites by transferring electrons from the NiV-LDH site to CoS, which boosts the formation of the NiOOH active phase, enhancing the catalytic performance in a 1 M KOH solution. While coupled with the heterostructure CoS@NiV-LDH as the anode and cathode, it demands a cell voltage of just 1.57 V to attain a current density of 10 mA cm–2 with remarkable stability for 70 h. Density functional theory (DFT) calculations reveal improved catalytic activity toward the oxygen evolution reaction (OER) for CoS@NiV-LDH with a lower energy barrier originating from the charge transfer-induced synergistic mechanism at the CoS and NiV-LDH interface. Moreover, the observed downshift of the d-band center for the CoS@NiV-LDH heterostructure explains their enhanced performance toward the hydrogen evolution reaction (HER), facilitating the H* adsorption/desorption process.