Converting CO₂ into renewable fuel via photocatalysis is of significance to solving the energy crisis and climate change. However, the limited electron transfer in single catalysts always limits the reduction reaction. In this work, a p-n heterojunction was constructed between Cr doped MgAl–LDH (abbreviated as LDH) and Co₃O₄ for visible-light-driven fuel production. Since LDH and Co₃O₄ both have the sufficient potentials to drive CO₂ photoreduction, the constructed type-II heterojunction is more favorable for electron utilization efficiency. The optimal Co₃O₄/LDH heterojunction exhibited the highest CO evolution rate of 7.42 μmol•g⁻¹•h⁻¹ and a CO selectivity of 90.5% with TEOA as sacrificial agent. The further characterizations highlight that the addition of Co₃O₄ greatly improves the light absorption and the heterojunction effectively promotes the reverse migration of electrons and holes. This work investigates and verifies the designed type-II heterojunction based on MgAl–LDH, which has the guidance for the design of heterojunction catalysts and promotes the practical application of MgAl–LDH in photocatalytic region.