Atomically　precise　metal　nanoclusters　(NCs)　have　garnered　enduring　interest　in　account　of　peculiar　atomic　stacking　mode,　discrete　energy　band　structure,　and　abundant　active　sites,　which　are　distinct　from　conventional　metal　nanocrystals.　None-theless,　research　works　on　metal　NCs-based　photosystems　are　still　in　the　infant　stage　in　terms　of　generic　light-induced　instability,　deficiency　of　metal　NCs　with　photosensitization　effect　to　trigger　photoredox　catalysis,　and　a　complicated　interfacial　charge　transport　process.　Herein,　we　concisely　overview　the　latest　concerted　endeavors　in　constructing　metal　NCs-based　photosystems　for　heterogeneous　photocatalysis　and　photoelectrochemical　water　splitting　with　particular　emphasis　focusing　on　elucidating　the　charge　transfer　characteristics　of　metal　NCs.　Moreover,　objective　discussion　and　personal　opinions　on　quintessential　works　are　specifically　provided.　Future　perspectives　and　challenges　of　metal　NCs-based　photosystems　are　eventually　highlighted.　We　hope　this　perspective　article　would　inspire　ongoing　interest　in　unleashing　the　emerging　potentials　of　atomically　precise　metal　NCs　for　solar　energy　conversion.