Crafting　spatially　controllable　charge　transfer　channels　at　the　nanoscale　level　remains　an　enduring　challenge　in　solar-to-chemical　conversion　technology.　Despite　the　advancements,　it　still　suffers　from　sluggish　interfacial　charge　transport　kinetics　and　scarcity　of　strategies　to　finely　modulate　charge　transport　pathways.　Herein,　this　article　demonstrates　the　unexpected　charge　modulation　property　of　non-conjugated　insulating　polymer　assisted　by　a　universal　layer-by-layer　self-assembly　tactic.　Oppositely　charged　poly(dimethyl　diallyl　ammonium　chloride)　(PDDA)　and　Ti3C2　MXene　quantum　dots　(MQDs)　are　periodically　attached　to　the　wide　bandgap　metal　oxides　(WMOs)　to　design　multilayered　heterostructured　photoanodes.　The　intermediate　PDDA　layer　acts　as　an　efficacious　charge　relay　medium　to　access　directional　electron　flow　from　WMOs　to　Ti3C2　MQDs,　while　Ti3C2　MQDs　serve　as　the　electron　extractor.　Charge　transfer　cascade　is　thus　stimulated　on　account　of　the　simultaneous　electron-trapping　capabilities　of　interim　PDDA　layer　and　Ti3C2　MQDs,　which　synergistically　favors　the　conspicuously　boosted　charge　separation　over　WMOs,　affording　the　WMOs/(PDDA/MQDs)n　photoanodes　with　considerably　enhanced　photoelectrochemical　(PEC)　water　oxidation　performances.　Moreover,　PEC　performances　of　such　photoanodes　can　be　tuned　by　interface　configuration　via　assembly　number　and　sequence.　This　work　will　provide　an　insightful　perspective　to　craft　a　directional　charge　transfer　pathway　through　insulating　polymer　for　solar　energy　conversion.　©　2022　Wiley-VCH　GmbH.