For the first time, we report a copper nanoclusters based fluorescence sensor for hemoglobin (Hgb). Aggregation induced quenching of tannic acid capped copper nanoclusters' (TACuNCs) fluorescence by the Hgb-H2O2 mixture which mimics the Fenton's reagent is used here for the selective determination of Hgb. It is possible to effectively determine Hgb using this sensitive and cost-effective sensor in the linear range 5.0×10 -8 M to 4.0×10 -9 M with a limit of detection 5.6×10 -10 M. The practical utility of the sensor is evident from the good recovery values obtained from Hgb spiked with artificial blood serum.