Exceptional　temperature　sensitivity　and　the　resulting　luminescence　response　position　perovskite　materials　as　potent　contenders　in　wearable　sensing　devices.　However,　the　mechanisms　driving　temperature-induced　fluorescence　reversibility,　especially　across　an　ultrawide　temperature　range　or　at　freezing　temperatures,　remain　poorly　understood.　In　this　study,　we　systematically　elucidate　the　mechanisms　governing　temperature-induced　fluorescence　reversibility　in　CsPbBr3/PS　composite　and　astonishingly　observe　the　reversible　fluorescence　enhancement　under　freezing　temperatures　for　the　first　time.　Elevated　temperature-induced　lattice　phase　transitions　and　freezing　temperature-associated　lattice　distortions　in　CsPbBr3　can　modulate　the　electrons＇　non-radiative　recombination　process,　leading　to　temperature-dependent　fluorescence　quenching　and　enhancement,　respectively.　Notably,　these　structural　perturbations　can　be　reversed　with　temperature　cycling,　ensuring　the　reversibility　of　thermally　induced　fluorescence　phenomena.　Leveraging　these　insights,　we　develop　a　CsPbBr3/PS-based　wearable　temperature　sensor　that　operates　over　an　ultrawide　range　(263　K　∼　423　K)　with　high　precision　(error　margin　within　±　10　%).　Our　findings　highlight　the　significant　breakthrough　of　CsPbBr3　in　temperature　sensing　and　wearable　applications.　©　2025　Elsevier　Ltd