The phenylphosphinic acid-functionalized microspheres were successfully prepared by "one-pot" emulsion polymerization of styrene/divinylbenzene with a functional macromolecular reversible addition-fragmentation chain transfer (RAFT) agent, poly(3-[2-(zicryloyloxy)ethoxy]-3-oxopropyl(phenyl)phosphinic acid)-block-polystyrene (P(AOPA)-b-PSt), as an amphiphilic emulsifier. The monodisperse microspheres were obtained with about 300 nm of the diameters and the clear core-shell structures, while phenylphosphinic acid groups were introduced into the shell via the RAFT process. The functionalized microspheres show high ability to coordinate with Cu2+ or Fe3+.