A novel 1,8-naphthalimide-based chemosensor was designed and synthesized for rapid recognition of Cr3+. The desired sensor showed off-on fluorescent and lifetime-based response upon Cr3+ and S2− in solution, on test paper and in cells. With the intensity-based method, the limit of quantification (LOQ) value was 0–5.5 × 10–5 M and the detection limit could be as low as 0.60 ppm. The 'in situ' prepared Cr3+ complex can recognize S2− among a series of common anions with high selectivity and sensitivity, the LOD can be as low as 307 nM. The lifetime of the sensor changes from 4.95 to 4.89 and further to 5.88 ns upon addition of Cr3+ and S2− in turn.