Natural photosynthesis plays an important role in maintaining environmental carbon balance. Taking inspiration from this, we developed a light-driven, enzymatic nanosystem for the highly selective production of formic acid from CO₂. The system combines photocatalytic graphitic carbon nitride (g-C₃N₄) with two natural enzyme catalysts, carbonic anhydrase (CA) and formate dehydrogenase (FateDH), encapsulated in ZIF-8, a porous metal-organic framework (MOF). Efficient in situ regeneration of reduced nicotinamide adenine dinucleotide (NADH) is realized through visible-light irradiation of g-C₃N₄ with a suitable redox potential (-0.3 V (NHE)). The introduction of ZIF-8 ensures a large amount of loaded protein with little damage to enzyme activity, and its encapsulation of CA and FateDH shortens the distance between the enzymes. This is conducive to increasing the diffusion of substances during the CO₂-to-formic acid cascade reaction, thus improving the reaction efficiency. This work is expected to provide new insight into the design and development of highly selective, artificial photosynthesis systems to efficiently convert CO₂ into fuels, chemicals, and other materials.