Metal-organic frameworks (MOFs) have exhibited huge potential in the field of CO2 electroreduction but highly stable and active ones are still scarce. This study reports a (5,10,15,20-tetrakis(4-carboxyphenyl)porphyrinato)-Fe(iii) chloride (FeTCPPCl) co-building UiO-66 electrocatalyst for CO2 reduction in an aqueous solution. In situ X-ray absorption spectroscopy (XAS) measurements characterized its robust structure under catalysis. The unique framework of UiO-66 provides the available proton facilitator for improving CO2 reduction activity on iron porphyrin, and a concerted proton-electron transfer (CPET) mechanism might be considered for the catalytic pathway, achieving the highest faradaic efficiency of nearly 100% at an overpotential of 450 mV for turning CO2 to CO in the reported MOFs.