An aggregation-induced emission (AIE) based “turn-on” fluorescent chemodosimeter for selective detection of Pb²⁺ions has been developed by making use of the strong affinity of lead ions for phosphate residues. The probe is a phosphate functionalized tetraphenylethylene derivative and the resulting lead–TPE complex has very low solubility in working solvent and triggers aggregation induced emission. The probe is highly efficient, cost-effective and shows a low detection limit of 10 ppb.