The fast and sensitive detection of copper ions would be essential for water monitoring. Herein, we report a novel development of impedimetric sensor based on carbon dots/chitosan nanocomposite. Carbon dots (CDs) were synthesized by simple heating of acidic aqueous solution of glucose. The CDs were characterized by TEM, FTIR, XRD, UV-visible, and PL. These measurements revealed that the CDs possess a mean size of 3.2 nm, graphitic structure with carboxyl and hydroxyl groups on the surface, and show particular optical properties. A glassy carbon electrode (GCE) was modified with a carbon dots/chitosan (CHITO) nanocomposite, and was characterized by transmission electron microscopy and electrochemical impedance spectroscopy (EIS). The CDs-CHITO/GCE electrode exhibits large surface area, good conductivity lm, and charge transfer at interface lm/electrolyte. The proposed impedimetric sensor exhibits a linear response to Cu(II) over 10 -9 M to 10 -5 M rang with a limit of detection at about 5×10 -10 M. In addition, the sensor shows good selectivity toward Cu(II) ions, which is less than 5 %.Therefore, the as-developed impedimetric sensor exhibits good reproducibility, stability, selectivity, and a low limit of detection, which augur well for its application in water safety control processes.