Transition　metal　chalcogenides　quantum　dots　(TMCs　QDs)　nanocrystals　are　featured　by　large　absorption　coefficient,　abundant　active　sites,　and　quantum　confinement　effect,　rendering　them　emerging　light-harvesting　antennas　for　solar　energy　conversion.　Although　diverse　TMCs　QDs-based　photosystems　have　been　explored　for　multifarious　photoredox　catalysis,　an　elaborate　and　comprehensive　summary　on　TMCs　QDs-based　solar-to-hydrogen　conversion　has　been　rarely　reviewed.　In　this　Review,　we　elucidate　the　fundamental　physicochemical　properties　of　TMCs　QDs　(e.g.,　CdS　QDs,　CdSe　QDs,　CdTe　QDs,　etc.)　currently　being　extensively　investigated　along　with　synthesis　methodologies.　Modification　strategies　for　boosting　photocatalytic　water　splitting　performances　of　TMCs　QDs,　such　as　cocatalyst　loading,　heterojunction　engineering,　element　doping,　and　plasmonic　metal　photosensitization,　are　then　specifically　introduced.　Besides,　we　present　detailed　information　on　the　latest　advances　on　the　photocatalytic　hydrogen　generation　involving　sacrificial　reagents,　Z-scheme　photosystems,　one-step　excitation　photosystems　for　overall　water　splitting,　and　photosensitizers　endowed　by　molecular　catalysts,　metal-organic　frameworks,　or　conjugated　polymers.　Finally,　future　outlook　and　challenge　on　the　development　of　TMCs　QDs-dominated　photocatalysis　are　highlighted.　It　is　anticipated　that　our　Review　would　inspire　ongoing　interest　in　unleashing　the　great　potential　of　TMCs　QDs　nanocrystals　for　solar　energy　conversion.　©　2023　American　Chemical　Society.