Owing to the multiple proton-coupled electron transfer steps involved in the electrochemical carbon dioxide reduction reaction (CO2RR), single-atom catalysts (SACs) are ideal platforms for studying such complex chemical reaction processes. The structural simplicity and homogeneity of SACs facilitate the understanding of the structure-performance relationship and reaction mechanisms of the CO2RR. Operando attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) is a valuable tool to identify the dynamic intermediate transformation processes in the CO2RR occurring on SACs and to study the impact of local reaction environments on the CO2RR performance. This article reviews operando ATR-SEIRAS and its key applications in the SAC-catalyzed CO2RR. The review briefly introduces the surface enhancement mechanism of electrochemical in situ infrared spectroscopy, formation mechanisms of the C1 and C2 products, function of operando ATR-SEIRAS in investigating the mechanisms of single-/dual-atom catalysts in converting CO2/CO to C1 and C2 products, and methods of using spectroscopic information to determine the interfacial H2O and local pH at the electrode. Finally, the review provides perspectives on the future development of operando ATR-SEIRAS.