Double-site catalysts have attracted widespread attention in the field of electrocatalysis due to their high metal loading, adjustable active centres, and electronic valence states. However, the development of bimetallic sites catalysts that coordinate with definite atoms is still in the exploratory stage. Here, we designed and synthesized a bimetallic palladium complex (BPB-Pd₂) with conjugated backbone. The supported BPB-Pd₂ was applied to electrochemical CO₂ reduction reaction (CO₂RR) for the first time. The as-obtained BPB-Pd₂ gives an exceptional Faradaic efficiency of CO (FE_CO) of 94.4% at −0.80 V vs. reversible hydrogen electrode (RHE), which is significantly superior to monoatomic palladium catalyst (BPB-Pd₁). The density functional theory (DFT) calculations revealed that the essential reason for the outstanding activity of BPB-Pd₂ toward CO₂RR was that the electronic effect between diatomic palladium reduces the free energy change for CO₂RR process. Thus, BPB-Pd₂ exhibits moderate free energy change to form COOH* intermediate, which was beneficial for the generation of CO in CO₂RR.