We developed a tandem electrocatalyst for CO2‐to‐CO conversion comprising the single Cu site co‐coordinated with N and S anchored carbon matrix (Cu‐S1N3) and atomically dispersed Cu clusters (Cux), denoted as Cu‐S1N3/Cux. The as‐prepared Cu‐S1N3/Cux composite presents a 100 % Faradaic efficiency towards CO generation (FECO) at −0.65 V vs. RHE and high FECO over 90 % from −0.55 to −0.75 V, outperforming the analogues with Cu‐N4 (FECO only 54 % at −0.7 V) and Cu‐S1N3 (FECO 70 % at −0.7 V) configurations. The unsymmetrical Cu‐S1N3 atomic interface in the carbon basal plane possesses an optimized binding energy for the key intermediate *COOH compared with Cu‐N4 site. At the same time, the adjacent Cux effectively promotes the protonation of *CO2− by accelerating water dissociation and offering *H to the Cu‐S1N3 active sites. This work provides a tandem strategy for facilitating proton‐coupled electron transfer over the atomic‐level catalytic sites. A tandem catalyst composed of single Cu sites co‐coordinated with N and S and atomically dispersed Cu clusters (Cu‐S1N3/Cux) was developed for CO2‐to‐CO conversion. The Cu‐S1N3/Cux exhibited a 100 % Faradaic efficiency for CO formation (FECO), outperforming the single‐atomic Cu‐N4 analogue (FECO=54 %).