Photocatalysis　represents　an　emerging　technology　for　solving　the　deteriorating　energy　crisis　and　environmental　problems　by　directly　harvesting　green,　renewable,　and　sustainable　solar　energy.　Due　to　the　maximum　atomic　utilization　efficiency,　tunable　electronic　structures　and　outstanding　catalytic　activities,　single-atom　catalysts　(SACs)　have　emerged　as　promising　candidates　for　photocatalysis.　Although　many　reviews　on　single-atom　photocatalysis　have　been　reported　in　the　past　few　years,　a　comprehensive　review　devoted　to　specifically　elucidating　the　generic　characteristics　of　SACs　in　heterogeneous　photocatalysis　has　so　far　not　yet　appeared.　In　this　review,　we　summarize　the　latest　progress　in　SACs　mediated　photocatalysis　paired　with　diverse　photocatalytic　mechanisms　from　a　fresh　insight.　Firstly,　we　elucidate　the　various　synthetic　strategies　for　SACs　with　a　focus　on　the　advantages　and　disadvantages　of　each　approach.　Subsequently,　state-of-the-art　characterization　methods　utilized　for　unleashing　the　fine　structures　of　single-atom　photocatalysts　have　been　concisely　overviewed.　Furthermore,　widespread　applications　of　SACs　in　diverse　photocatalytic　redox　reactions　are　comprehensively　introduced.　Finally,　the　remaining　challenges　and　future　opportunities　in　this　booming　research　field　are　outlooked　for　guiding　the　rational　design　of　robust,　stable,　and　high-performance　SACs.　Our　review　could　inspire　sparkling　ideas　on　how　to　smartly　utilize　single　atoms　for　crafting　high-efficiency　artificial　photosystems　towards　solar　energy　conversion.