Promoting the separation of photo-generated carriers is significantly important to improve the efficiency of photocatalytic hydrogen production. Therefore, we prepared g-C₃N₄/CeCO₃OH/CeO₂ (CeCeCN) ternary nanocomposite via an easy synthetic way using g-C₃N₄ and CeO₂ as reactants. A CeCO₃OH layer was formed and resulted in the novel ternary photocatalyst. The CeCeCN composite shows superior photocatalytic (PC) H₂ generation performance in sunlight excitation. The H₂ evolution rate is about 764 μmol h⁻¹ g⁻¹, which is over 11 times larger than those of g-C₃N₄ and CeO₂. Compared with g-C₃N₄ and CeO₂, CeCeCN further shows a larger photo-response current density and a lower charge-transfer resistance. The remarkably increased photocatalytic property of CeCeCN is because of the efficient charge migration induced by the formed heterojunction. Our findings demonstrate that building multi-heterostructures can liberate more excited electrons for efficient hydrogen production under sunlight.