The　development　of　an　instrument-free,　on-site,　real-time,　sensitive,　and　visualized　fluoride-ion　(F-)　content　rapid　detection　strategy　is　crucial　to　ensuring　the　health　of　the　population.　Smart　microdevices　that　are　portable,　directly　read,　and　easy　to　operate　have　recently　attracted　much　attention.　Herein,　a　ratiometric　fluorescent　probe　(AA-CDs@[Ru(bpy)3]2+)-based　smartphone　sensing　platform　was　developed　for　the　detection　of　F-.　The　red　fluorescent　ruthenium　bipyridine　[Ru(bpy)3]2+　molecule　was　chosen　as　the　reference　signal,　and　the　carbon　dots　(AA-CDs)　with　Al3+　aggregation-induced　enhanced　emission　(AIE)　were　designed　as　the　response　signal.　The　ratiometric　probe　fluorescence　changed　continuously　from　red　to　cyan　in　response　to　different　concentrations　of　F-,　and　the　red-green-blue　(RGB)　channel　values　of　the　fluorescence　image　were　extracted　through　the　smartphone　color　recognition　application　(APP).　There　was　a　linear　relationship　between　the　blue-red　(B/R)　ratio　and　the　F-　concentration,　with　a　limit　of　detection　(LOD)　of　1.53　μM,　far　below　the　allowable　content　of　F-　in　drinking　water　prescribed　by　the　World　Health　Organization.　The　F-　content　was　rapidly　detected　on-site　with　satisfactory　repeatability　and　relative　standard　deviation　using　several　water　and　toothpaste　samples　as　the　real　sample.　The　platform　features　low　cost,　portability,　easy　operation,　and　good　stability,　selectivity,　and　repeatability,　which　provides　a　powerful　tool　for　the　visual　quantitative　detection　of　smartphone-based　microsensing　platforms　possibly　in　the　fields　of　environmental　protection,　diagnosis,　and　food　safety　assessment.　©　2023　American　Chemical　Society.