In the present work, metallothionein isolated from rabbit liver is decorated onto the surface of supported C-dots to form a novel sorbent for the selective adsorption and removal of cadmium. The adsorption behaviors of cadmium, including the pH-dependent adsorption, the sorption capacity and selectivity, the sorption kinetics and isotherms, are investigated. This novel composite is successfully applied for the removal of cadmium in environmental waters.