Graphitic　carbon　nitride　(CN)　is　a　versatile　polymeric　nanosheet　that　has　gained　significant　attention　due　to　its　stability,　tunable　band　structure,　and　eco-friendliness.　This　review　explores　recent　advances　in　CN-based　material　design　and　construction,　such　as　element　doping,　heterostructure　formation,　and　surface　sensitization,　emphasizing　their　unique　optoelectronic　and　charge　transfer　properties.　Subsequently,　their　potential　applications　in　photocatalysis　for　environmental　remediation,　and　energy　generation,　as　well　as　organic　synthesis　and　medical　diagnostics　are　also　delved.　This　review　critically　explores　these　advances　and　their　challenges,　and　offers　future　perspectives　to　enhance　the　performance　of　CN-based　materials　and　contribute　to　a　sustainable　future.{GRAPHICAL　ABSTRACT}