To date, the efficient photocatalytic conversion of CO₂ into high-value C2 products remains a great challenge. Herein, the Au-CeO₂ nanocomposite with Au-O-Ce sites at the micro-interface was developed to achieve a highly selective conversion of CO₂ into C₂H₆. This can be partially ascribed to the formation of key intermediates of COCO* was confirmed via in-situ Fourier transform infrared (FTIR) spectroscopy, indicating that the Au-CeO₂ micro-interface could prompt the multi-electron reduction of CO* before desorption, and enable the production of C2 species. Moreover, theoretical calculations suggested that Au-O-Ce sites at the micro-interface could reduce the energy barriers for the formation of COOH* and COCO*, facilitating the production of C₂H₆. Therefore, the Au-CeO₂ nanocomposite exhibited a C₂H₆ production rate of 11.07 µmol g⁻¹ h⁻¹ and high electron selectivity of 93.1 % (product selectivity: 65.3 %), which is comparable with most state-of-the-art photocatalysts.