Rational　design　of　heterojunctions　as　photocatalysts　that　can　help　alleviate　the　energy　and　environmental　crisis　relies　on　the　efficient　electron　transfer　to　the　catalytically　active　sites.　In　this　work,　a　robust　metal-organic　framework　(MOF)-based　heterostructured　catalyst　for　the　CO2　reduction　reaction　(CRR)　was　reported,　taking　advantage　of　a　synergy　effect　between　ultrathin　(1.5　nm　thickness)　Ni-rich　Ni(OH)(2)　nanosheets　(NSs)　and　the　highly　stable　and　conductive　Fe-rich　Prussian　blue　(PB).　This　Ni(OH)(2)/PB　photocatalyst　can　attain　an　optimal　CO　evolution　rate　of　108.8　mmol　h(-1)　g(-1)　and　a　high　CO　selectivity　(88.2-95.0%)　in　the　CRR.　The　stable　PB　helps　atomically　thin　Ni(OH)(2)　NSs　to　be　well　dispersed　and　exposed　in　the　heterojunction.　A　built-in　electric　field　found　at　the　interface　of　the　bulk-sized　PB　and　the　ultrathin　Ni(OH)(2)　further　directs　the　electron　transfer.　Intriguingly,　the　conductive　PB　can　quickly　capture　the　electrons　from　the　Ru-based　photosensitizer　and　then　rapidly　sends　them　to　the　CRR-active　Ni(OH)(2)　in　the　Z-scheme　Ni(OH)(2)/PB　system,　accounting　for　its　high　efficiency　and　high　selectivity　over　CO2　reduction　into　CO.　The　findings　underline　the　versatility　and　the　mechanistic　response　of　MOFs　in　constructing　advanced　catalysts.