Exposure to heavy metal ions, even at very mild concentration limits is very hazardous to all living creatures on earth. The development of reliable and sensitive molecules to detect these toxic ions is of considerable interest. Great efforts have been done by researchers to develop chemosensors, especially fluorescent probes to detect these toxic ions. In this review, the recently reported cadmium and mercury ion sensors are briefly discussed and summarized. Chemosensors are categorized based upon the nature of fluorophoric unit as well as receptor moiety.