In sustainable hydrogen generation, photoelectrochemical (PEC) water splitting stands as a crucial technology, offering solutions to the global energy crisis while tackling environmental challenges. PEC water splitting relies on metal oxide nanostructures due to their unique electronic and optical characteristics. This research highlights the development of a CuO-Fe₂O₃@g-C₃N₄ nanocomposite, created through the integration of three components and fabricated via a one-pot hydrothermal process, precisely engineered to enhance PEC water-splitting efficiency. The combination of CuO, Fe₂O₃, and g-C₃N₄ results in a unified heterojunction structure that efficiently mitigates issues associated with charge carrier recombination and structural stability. Additionally, the analyses of both the structure and composition confirmed the precise synthesis of the composite. The CuO-Fe₂O₃@g-C₃N₄ nanocomposite achieved a photocurrent density of 1.33 mA cm⁻² vs. Ag/AgCl upon exposure to light, demonstrating superior PEC performance and outperforming the individual CuO and Fe₂O₃ components. The enhanced performance is attributed to g-C₃N₄ acting as a photoactive material, generating charge carriers, while the combination of CuO-Fe₂O₃ enables efficient carrier separation and mobility. This synergistic interaction significantly enhances photocurrent generation and ensures long-term stability, positioning the material as a highly promising solution for sustainable hydrogen production. These results highlight the promise of hybrid nanocomposites in driving progress in renewable energy technologies, opening new avenues for the development of more efficient and long-lasting PEC systems.