MoS 2 @NiFeCo-LDH and MoS 2 @NiFeCo-Mo(doped)-LDH were found to have very low OER and HER overpotentials of 156 (195) mV and 61 (102) mV at 10 mA cm -2 under light irradiation (dark condition), respectively. In comparison to NiFeCo-NF, the MoS 2 @NiFeCo-Mo(doped)-LDH and MoS 2 @NiFeCo-LDH heterostructures demonstrated significantly enhanced reaction kinetics and improved light absorption efficiency; these experimental findings are tentatively attributed to the large atomic radius of the high-valence Mo dopant and the photo-responsive nature of MoS 2 QDs, which together change the (photo)electrodes intrinsic HER and OER activity, lead to catalyst amorphization, and increase the effective catalytic surface area. Our DFT studies show that the incorporation of MoS 2 increases the intrinsic electrocatalytic activity of NiFeCo-LDH and NiFeCo-Mo(doped)-LDH towards OER and HER, respectively. The increased activities are due to changes in the electronic structure, reaction thermodynamics, and the reaction mechanism. MoS 2 makes the catalysts metallic and hence enhances their conductivity. MoS 2 QD deposition reduces the free energy barriers of both HER; the incorporation of MoS 2 QDs leads to a nearly ideal *H adsorption energy. In OER, MoS 2 changes and facilitates the rate-determining step of OOH * formation at smaller overpotentials; this is also supported by the experimental results. Finally, the MoS 2 @NiFeCo-Mo(doped)-LDH and MoS 2 @NiFeCo-LDH electrodes exhibit remarkable activity and stability for the overall water splitting efficiency, resulting in potentials of 1.46 (1.54) V at 10 mA cm -2 , under light (dark) conditions.