Silver-based catalysts are among the most promising materials for the electrochemical CO₂ reduction reaction (CO₂RR), but they predominantly produce carbon monoxide (CO), limiting their utility in generating higher-value multi-carbon products. Here, we report a facile confined etching and epitaxial growth strategy to synthesize “corn-shaped” AgPd@Cu core–shell nanowires. The unique structure of the “corn-shaped” AgPd@Cu nanowires is conducive to the efficient generation and maintenance of high local CO concentration, and provides the optimal active sites for the dimerization reaction of CO. It enables a critical transition from C₁ to C₂ product formation, achieving a Faradaic efficiency of 38.80% for ethylene (C₂H₄) at −1.50 V vs. reversible hydrogen electrode (RHE) with outstanding catalytic stability. This architecture (corn-shaped) is expected to enhance the catalytic performance due to the increased surface area and interface synergy. The interfacial synergy between the AgPd core and Cu shell selectively suppresses the hydrogen evolution reaction and promotes the C–C coupling, facilitating enhanced CO₂-to-C₂ conversion. This study not only addresses the challenge of C–C bond formation in CO₂RR but also presents a generalizable strategy for constructing robust, multi-metallic nanocatalysts capable of operating under strongly reducing conditions.