The　keto-switched　photocatalysis　of　covalent　organic　frameworks　(COFs)　for　efficient　H2　evolution　was　reported　for　the　first　time　by　engineering,　at　a　molecular　level,　the　local　structure　and　component　of　the　skeletal　building　blocks.　A　series　of　imine-linked　BT-COFs　were　synthesized　by　the　Schiff-base　reaction　of　1,　3,　5-benzenetrialdehyde　with　diamines　to　demonstrate　the　structural　reconstruction　of　enol　to　keto　configurations　by　alkaline　catalysis.　The　keto　groups　of　the　skeletal　building　blocks　served　as　active　injectors,　where　hot　π-electrons　were　provided　to　Pt　nanoparticles　(NPs)　across　a　polyvinylpyrrolidone　(PVP)　insulting　layer.　The　characterization　results,　together　with　density　functional　theory　calculations,　indicated　clearly　that　the　formation　of　keto-injectors　not　only　made　the　conduction　band　level　more　negative,　but　also　led　to　an　inhomogeneous　charge　distribution　in　the　donor-acceptor　molecular　building　blocks　to　form　a　strong　intramolecular　built-in　electric　field.　As　a　result,　visible-light　photocatalysis　of　TP-COFs-1　with　one　keto　group　in　the　skeletal　building　blocks　was　successfully　enabled　and　achieved　an　impressive　H2　evolution　rate　as　high　as　0.96　mmol　g−1　h−1.　Also,　the　photocatalytic　H2　evolution　rates　of　the　reconstructed　BT-COFs-2　and　-3　with　two　and　three　keto-injectors　were　significantly　enhanced　by　alkaline　post-treatment.　©　2023　Wiley-VCH　GmbH.