Electrochemical CO₂ reduction reaction (CO₂RR) has received great attention in the past few decades as a promising process for reducing CO₂ emissions and producing high-value chemicals. However, the rational design of catalysts for CO₂RR continues to represent a significant challenge; hence, it is essential to understand the structure–property relationship and how catalysts facilitate CO₂ conversion. Herein, the tetrahedral site occupancy and octahedral site occupancy of spinel CuAl₂O₄ were modulated by constructing CuAl₂O₄/CeO₂ heterointerface, and the effect on CO₂RR performance was further investigated. In this work, we demonstrated that the octahedral site occupancy increases after constructing CuAl₂O₄/CeO₂ heterointerface, leading to a significant improvement in the catalyst’s ability to absorb and activate CO₂ and enhance *CO coverage. Meanwhile, the unique oxyphilic property of CeO₂ enhances OH coverage and maintains the local pH on the catalyst surface. Ultimately, CuAl₂O₄/CeO₂ achieved 70.4% multi-carbon (C₂₊) products Faraday efficiency (FE) in the flow cell and operated stably for over 35 h at a current density of 200 mA·cm⁻² under 1 M KOH. CuAl₂O₄/CeO₂ exhibits completely different CO₂RR performance compared to pure CuAl₂O₄, providing new insights into accurate regulation of spinel structure.