The　core　factors　dictating　the　photocatalysis　efficiency　are　predominantly　centered　on　controllable　modulation　of　anisotropic　spatial　charge　transfer/separation　and　regulating　vectorial　charge　transport　pathways.　Nonetheless,　the　sluggish　charge　transport　kinetics　and　incapacity　of　precisely　tuning　interfacial　charge　flow　at　the　nanoscale　level　are　still　the　primary　dilemma.　Herein,　we　conceptually　demonstrate　the　elaborate　design　of　a　cascade　charge　transport　chain　over　transition　metal　chalcogenide-insulating　polymer-cocatalyst　(TIC)　photosystems　via　a　progressive　self-assembly　strategy.　The　intermediate　ultrathin　non-conjugated　insulating　polymer　layer,　i.e.,　poly(diallyl-dimethylammonium　chloride)　(PDDA),　functions　as　the　interfacial　electron　relay　medium,　and　simultaneously,　outermost　co-catalysts　serve　as　the　terminal　＇electron　reservoirs＇,　synergistically　contributing　to　the　charge　transport　cascade　pathway　and　substantially　boosting　the　interfacial　charge　separation.　We　found　that　the　insulating　polymer　mediated　unidirectional　charge　transfer　cascade　is　universal　for　a　large　variety　of　metal　or　non-metal　reducing　co-catalysts　(Au,　Ag,　Pt,　Ni,　Co,　Cu,　NiSe2,　CoSe2,　and　CuSe).　More　intriguingly,　such　peculiar　charge　flow　characteristics　endow　the　self-assembled　TIC　photosystems　with　versatile　visible-light-driven　photoredox　catalysis　towards　photocatalytic　hydrogen　generation,　anaerobic　selective　organic　transformation,　and　CO2-to-fuel　conversion.　Our　work　would　provide　new　inspiration　for　smartly　mediating　spatial　vectorial　charge　transport　towards　emerging　solar　energy　conversion.　©　2024　The　Royal　Society　of　Chemistry.