In the present work, we studied a unique and facile method for the drastic structural transformation of hydrophobic small CdE (E = S, Se, Te) nanoparticles into large, high-quality pencil-shaped nanoparticles through an Ostwald ripening process induced by Cl(-) and surfactants (oleic acid and oleylamine). This study revealed that Cl(-) is the effective anion for the controlled structural transformation of CdE nanoparticles. This transformation reaction can be readily extended to the formation of various functional materials.