We present the photoelectrochemical (PEC) regeneration of nicotinamide cofactors (NADH) coupled with the enzymatic synthesis of formate from CO2 towards mimicking natural photosynthesis. The water oxidation-driven PEC platform exhibited high yield and the rate of NADH regeneration was compared to many other homogeneous, photochemical systems. We successfully coupled solar-assisted NADH reduction with enzymatic CO2 reduction to formate under continuous CO2 injection.