Metal　semiconductor　heterostructures　have　been　arousing　enduring　interest　on　account　of　the　pivotal　roles　of　metal　nanocrystals　(NCs)　as　interfacial　Schottky　junction-induced　charge　flow　mediators　and　surface　plasmon　resonance-triggered　photosensitizers.　Tungsten　oxide　(WO3)　stands　out　among　fruitful　semiconductors　by　virtue　of　favorable　energy-level　alignment　and　light　absorption　capability,　but　slow　charge　transfer　rate,　especially　the　sluggish　hole　transport　kinetics　and　short　life　span　of　charge　carriers,　retards　its　widespread　photocatalytic　applications.　In　this　work,　an　efficient　and　unidirectional　charge-transfer　channel　was　constructed　in　the　in　situ-formed　gold　nanoparticle　(Au　NP)-decorated　WO3　[Au/WO3　nanorods　(NRs)]　heterostructures　which　were　constructed　by　a　facile,　green,　easily　accessible,　and　efficacious　layer-by-layer　(LbL)　self-assembly　strategy　at　ambient　conditions,　wherein　the　in　situ　generation　of　Au　NPs　and　the　morphology　transformation　of　WO3　NRs　to　a　mesoporous　ensemble　occur　simultaneously.　Moreover,　the　deposition　amount　of　Au　NCs　on　the　WO3　matrix　can　be　finely　tuned　by　the　assembly　cycle.　Intriguingly,　the　unique　integration　mode　of　Au　NPs　with　the　WO3　matrix　at　the　nanoscale　level　endowed　by　the　LbL　self-assembly　benefits　the　high-efficiency　extraction,　separation,　and　migration　of　energetic　charge　carriers　photoinduced　over　WO3　NRs.　It　was　found　that　self-assembled　Au/WO3　heterostructures　demonstrate　highly　efficient　and　versatile　photoredox　performances　toward　mineralization　of　organic　pollutants　and　photoreduction　of　heavy　metal　ions　under　both　simulated　solar　and　visible　light　irradiation,　substantially　outperforming　the　single　WO3　counterpart.　This　is　predominantly　ascribed　to　the　crucial　role　of　Au　NPs　as　electron　traps　rather　than　the　plasmonic　photosensitizers　to　accelerate　the　interfacial　electron　transfer,　thereby　considerably　enhancing　the　separation　and　prolonging　the　lifetime　of　photoinduced　electron-hole　pairs.　In　addition,　predominant　active　species　in　the　photoredox　catalysis　were　unambiguously　determined,　and　the　photocatalytic　mechanism　was　clearly　elucidated.　Our　work　would　open　up　new　frontiers　to　rationally　design　a　large　variety　of　metal-semiconductor　heterostructures　for　promising　solar　energy　conversion.