The　tertiary　structures　of　HSA　and　BSA　show　a　76　%　similarity,　and　the　abnormal　levels　of　HSA　in　body　fluids　can　cause　many　diseases.　Therefore,　accurate　quantification　of　HSA　and　effectively　distinguishing　HSA　from　BSA　have　significant　application　value　in　various　fields.　In　this　paper,　a　deep-red　fluorescent　probe,　NITH,　based　on　1,8-naphthalimide,　is　demonstrated　as　a　potential　tool　for　accurately　quantifying　HSA　and　distinguishing　HSA　from　BSA.　The　probe　not　only　exhibits　large　stokes　shift　(100　nm)　and　low　detection　limit　(4.61　μg/L,　0.0692　nM),　but　also　effectively　detects　HSA　by　entering　its　hydrophobic　cavity　and　emitting　red　fluorescence.　Furthermore,　NITH　is　capable　of　tracking　the　distribution　levels　of　HSA　within　the　cells　through　endogenous　and　exogenous　cellular　imaging.　The　application　of　NITH　spans　various　environments　such　as　cells,　zebrafish,　urine,　and　test　strips,　solidifying　it　as　an　effective　tool　for　HSA　detection.　©　2023　Elsevier　Ltd