Carbon　quantum　dots　(CQDs)　as　a　rising　star　of　carbon　nanomaterials,　by　virtue　of　their　unique　physicochemical,　optical　and　electronic　properties,　have　displayed　tremendous　momentum　in　numerous　fields　such　as　biosensing,　bioimaging,　drug　delivery,　optoelectronics,　photovoltaics　and　photocatalysis.　In　particular,　the　rich　optical　and　electronic　properties　of　CQDs　including　efficient　light　harvesting,　tunable　photoluminescence　(PL),　extraordinary　up-converted　photoluminescence　(UCPL)　and　outstanding　photoinduced　electron　transfer　have　attracted　considerable　interest　in　different　photocatalytic　applications　for　the　sake　of　full　utilization　of　the　solar　spectrum.　This　review　aims　to　demonstrate　the　recent　progress　in　the　synthesis,　properties　and　photocatalytic　applications　of　CQDs,　particularly　highlighting　the　fundamental　multifaceted　roles　of　CQDs　in　photoredox　processes.　Furthermore,　we　discuss　the　challenges　and　future　direction　of　CQD-based　materials　in　this　booming　research　field,　with　a　perspective　toward　the　ultimate　achievement　of　highly　efficient　and　long-term　stable　CQD-based　photocatalysts.　©　The　Royal　Society　of　Chemistry.