Atomically　precise　metal　nanoclusters　(NCs)　emerge　as　a　novel　class　of　photosensitizers,　distinguished　by　their　discrete　energy　band　structures　and　abundance　of　catalytically　active　sites;　however,　their　broader　adoption　in　heterogeneous　photocatalysis　remains　hindered　by　the　challenges　of　ultrashort　carrier　lifetimes,　limited　stability,　and　the　complexity　of　charge　transport　regulation.　In　this　work,　we　conceptually　design　the　metal　NCs　photosensitized　and　graphene　(GR)-encapsulated　transition　metal　chalcogenide　(TMC)　(GR/metal　NCs/TMCs)　heterostructure　via　a　cascade　electrostatic　self-assembly　strategy.　In　this　multilayer　ternary　heterostructure,　metal　NCs　are　integrated　between　TMCs　and　GR　nanosheets,　which　act　as　photosensitizers　for　enhancing　the　light　absorption　of　TMCs　and　meanwhile　increase　the　carrier　density　of　composite　photosystem.　The　favorable　interfacial　charge　transport　between　metal　NCs　and　TMCs　along　with　the　advantageous　electron-withdrawing　capability　of　GR　simultaneously　boosts　charge　separation　over　metal　NCs.　Benefiting　from　such　peculiar　carrier　transport　characteristics,　the　self-assembled　GR/metal　NCs/TMCs　heterostructure　demonstrates　remarkably　boosted　and　stable　photoactivities　toward　selective　photoredox　organic　transformation,　including　photocatalytic　anaerobic　reduction　of　aromatic　nitro　compounds　to　amino　derivatives　and　photocatalytic　oxidation　of　aromatic　alcohols　to　aldehydes　under　visible　light.　Furthermore,　the　mechanisms　underlying　the　photocatalytic　processes　are　elucidated　with　clarity.　Our　work　affords　a　quintessential　paradigm　for　customizing　atomically　precise　metal　NCs　in　engineered　photosystems　aimed　at　converting　solar　energy　into　chemical　energy.