Developing an efficient photocatalyst for solar-to-hydrogen production is regarded as a promising approach to tackle the energy and environmental challenges that we are currently facing. Herein, the TiO2–Cu2O nanocomposite is synthesized via a chemical reduction approach at ambient temperature and used as a photocatalyst. The composition and structure characterizations indicate that Cu2O particles are loaded on the surface of TiO2 nanospheres. The photocatalytic performance of the as-obtained materials is evaluated by a solar-to-hydrogen production test. It is found that the optimized TiO2–Cu2O nanocomposite (TC-20) exhibits a hydrogen evolution rate of 7139.02 μmol g−1 h−1, which is nearly 7 times that of pristine TiO2. Based on the photoluminescence spectra and photo/electrochemical measurements, the boosted photocatalytic H2 evolution performance comes from the promoted separation efficiency of photoinduced electron–hole pairs, which originates from the formed p–n heterojunction of the TiO2–Cu2O nanocomposite.