The　core　factors　affecting　the　efficiency　of　photocatalysis　are　predominantly　centered　on　controllable　modulation　of　anisotropic　spatial　charge　separation/transfer　and　regulating　vectorial　charge　transport　pathways　in　photoredox　catalysis,　yet　it　still　meets　with　limited　success.　Herein,　we　first　conceptually　demonstrate　the　rational　design　of　unidirectional　cascade　charge　transfer　channels　over　transition　metal　chalcogenide　nanosheets　(TMC　NSs:　ZnIn2S4,　CdS,　CdIn2S4,　and　In2S3),　which　is　synergistically　enabled　by　a　solid-state　non-conjugated　polymer,　i.e.,　poly(diallyldimethyl　ammonium　chloride)　(PDDA),　and　MXene　quantum　dots　(MQDs).　In　such　elaborately　designed　photosystems,　an　ultrathin　PDDA　layer　functions　as　an　intermediate　charge　transport　mediator　to　relay　the　directional　electron　transfer　from　TMC　NSs　to　MQDs　that　serve　as　the　ultimate　electron　traps,　resulting　in　a　considerably　boosted　charge　separation/migration　efficiency.　The　suitable　energy　level　alignment　between　TMC　NSs　and　MQDs,　concurrent　electron-withdrawing　capabilities　of　the　ultrathin　PDDA　interim　layer　and　MQDs,　and　the　charge　transport　cascade　endow　the　self-assembled　TMC/PDDA/MQD　heterostructured　photosystems　with　conspicuously　improved　photoactivities　toward　anaerobic　selective　reduction　of　nitroaromatics　to　amino　derivatives　and　photocatalytic　hydrogen　evolution　under　visible　light　irradiation.　Furthermore,　we　ascertain　that　this　concept　of　constructing　a　charge　transfer　cascade　in　such　TMC-insulating　polymer-MQD　photosystems　is　universal.　Our　work　would　afford　novel　insights　into　smart　design　of　spatial　vectorial　charge　transport　pathways　by　precise　interface　modulation　via　non-conjugated　polymers　for　solar　energy　conversion.