Metal/semiconductor　heterostructures　have　been　arousing　persistent　interest　on　account　of　prominent　roles　of　metal　nanocrystals　(NCs)　in　modulating　charge　transfer　in　photocatalysis.　It　has　been　generally　accepted　that　ligands　capped　on　the　tailor-made　metal　NC　surfaces　should　be　removed　for　exposing　more　active　sites,　and　the　interface　between　the　metal　and　semiconductor　should　be　clean　enough　to　facilitate　charge　flow.　Would　the　ligands　of　metal　NCs　definitely　deteriorate　charge　separation/transfer　and　what　is　its　correlation　with　photoactivity?　Inspired　by　this　motivation,　herein,　interface　configuration　between　the　metal　and　semiconductor　was　exquisitely　designed　by　a　ligand-triggered　electrostatic　self-assembly　strategy,　wherein　tailor-made　intrinsically　positively　charged　Pd　NCs　capped　with　hierarchically　branched　ligand　4-dimethylaminopyridine　(DMAP)　and　negatively　charged　surface-modified　CdS　nanowires　(NWs)　were　judiciously　utilized　as　the　building　blocks.　Significantly,　spontaneous　and　monodispersed　immobilization　of　Pd@DMAP　on　CdS　NWs　was　readily　initiated　by　DMAP　ligands,　which　endows　self-assembled　Pd@DMAP/CdS　NW　heterostructures　with　conspicuously　enhanced　and　versatile　photoreduction　performances　in　comparison　with　CdS　NWs　toward　anaerobic　photoreduction　of　aromatic　nitro　compounds,　photocatalytic　hydrogen　generation,　and　photoreduction　of　heavy　metal　ions　under　visible　light　irradiation,　owing　to　the　crucial　role　of　Pd@DMAP　for　efficaciously　capturing　electrons　without　the　inhibition　of　the　hierarchical　ligand　structure　and　interfacial　integration　mode.　More　intriguingly,　the　interfacial　distance　between　Pd@DMAP　and　CdS　NWs　was　finely　mediated　to　achieve　tunable　charge　transport.　Finally,　the　ligand-involved　photocatalytic　mechanism　was　elucidated.　It　is　anticipated　that　our　work　could　shed　new　insights　on　the　role　of　ligands　in　modulating　the　directional　charge　transfer　over　metal/semiconductor　photocatalytic　systems　for　substantial　solar　energy　conversion.　©　2019　American　Chemical　Society.