The efficacy of photocatalysts for green hydrogen (H2) production by solar-driven photocatalytic water splitting is still severely limited by ineffective charge separation, quick charge carrier recombination and low structural stability. In this study, a simple, low-temperature hydrothermal synthesis of CuS and ZnS (CZS) was used to rationally design a heterojunction photocatalyst, providing a simple and scalable method for improved photocatalytic performance. After 12 hours of continuous 1-sun irradiation, the CZS nanocomposite showed a remarkable cumulative H2 production of 12 145 µmol g−1, which is higher activity than that of the pristine CuS and ZnS. Additionally, the CZS heterojunction nanostructure has an ∼0.16% solar to hydrogen efficiency (STH). Extensive structural and spectroscopic investigations, including XRD, TEM, UV-vis absorption spectroscopy and XPS, revealed that the CZS exhibits the formation of a structured system with strong interfacial interactions. The proposed composite has unique physicochemical characteristics and synergistic interactions, supporting its increased photocatalytic activity. Improved light absorption and effective interfacial charge separation within the composite are responsible for the increased photocatalytic performance. This work highlights efficient and scalable solutions for solar-driven H2 production with earth-abundant sulphide materials for a viable hetero-structured system. This type of system with synergistic characteristics paves the way for a sustainable world towards decarbonization.