Abstract: Electrocatalytic CO₂ reduction reaction (CO₂RR) is playing an increasingly critical role in the recycling of carbon resources and the achievement of the “dual carbon” goals (carbon peak and carbon neutrality). However, the current catalytic performance of this technology still falls short of the demands for large-scale applications, necessitating the development of effective strategies to overcome existing performance bottlenecks. Most existing studies focus on tuning the intrinsic activity of catalysts by modulating the electronic structure of active sites to enhance catalytic performance, yet the performance gains from such single-dimensional regulation are gradually diminishing. Therefore, new regulatory directions are urgently needed to further improve catalytic performance. Against this backdrop, interface engineering has emerged as a highly promising strategy. By introducing exogenous components such as cations, anions, and functional molecules/polymers, it can effectively optimize the reaction microenvironment and modulate reaction energy barriers, offering a new direction for enhancing catalyst performance. This review starts from the interfacial structure of CO₂RR, systematically outlines the main strategies of interface engineering, highlights the direct and indirect mechanisms of cation regulation, summarizes relevant characterization and analysis methods, and further identifies key challenges and future directions in this field, aiming to provide new insights and theoretical guidance for the design and development of high-performance CO₂RR catalysts.