Increasing greenhouse gas emissions have resulted in greater motivation to find novel carbon dioxide (CO2) reduction technologies, where the reduction of CO2 to valuable chemical commodities is desirable. Molybdenum-dependent,formate dehydrogenase (Mo-FDH) from Escherichia coli is a metalloenzyme that is able to interconvert formate and CO, We describe a low-potential redox polymei; synthesized by a facile method, that contains cobaltocene (grafted to poly(allylumine), Cc-PAA) to simultaneously mediate electrons to Mo-FDH and immobilize Mo-FDH at the surface of carbon electrode. The resulting bioelectrode reduces CO2 to formate with a high Faradaic efficiency of 991 +/- 5 % at a mild applied potential of -0.66 V vs. SHE.