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Designing low-cost, highly efficient, and stable electrocatalysts for oxygen evolution reactions is of great significance for water splitting, which is a green and sustainable method of producing hydrogen. Herein, a series of transition metal sulphide-based nanostructures, including Au–CoNi2S4 core–shell, Au–NiS core–shell, Au–Co3S4 core–shell, and bare CoNi2S4 nanoparticles (NPs), have been rationally designed. Among them, the Au–CoNi2S4 core–shell NPs exhibit superior electrocatalytic properties for oxygen evolution. It requires an overpotential of only 264 mV to reach a current density of 10 mA cm−2, while the Tafel slope (35.6 mV dec−1) is also the lowest among the as-prepared nanostructures. X-ray photoelectron spectra and electrochemical impedance spectra demonstrate that the electronic structure and chemical state of Au–CoNi2S4 core–shell heterostructure are regulated by the delicate structural design. The enhanced electrocatalytic performance of the Au–CoNi2S4 core–shell heterostructure can be attributed to the combined effects of constructing bimetallic sulphide instead of its monometallic counterparts and forming metal–sulphide core–shell interface. It provides a way to develop a superior electrocatalyst by constructing a metal–bimetallic sulphide core–shell heterostructure. [ABSTRACT FROM AUTHOR]