We reported a facile and effective method for the preparation of highly branched polymers by combining the concepts of self-condensing vinyl polymerization (SCVP) and iodine transfer polymerization (ITP). This procedure used a chain transfer monomer synthesized in situ from a commercially available chloride compound, p-chloromethyl-styrene (CMS). The efficiencies of the halogen exchange from the alkyl chloride (-CH2Cl) to the alkyl iodide (-CH2I) at room and high temperature were studied using CMS and benzyl chloride as model halogenated compounds. The structures of the resulting polymer and the branching behavior were analyzed by nuclear magnetic resonance (NMR) spectroscopy and size-exclusion chromatography (SEC) equipped with a differential refractive index detector, a multiangle laser light scattering detector, and a viscometer detector. The model study using small molecules revealed that -CH2Cl could efficiently halogen exchange with sodium iodide (NaI) at both room and high temperature. The model linear polymerization in the presence of benzyl chloride and NaI confirmed the controlled nature of the polymerization. The results of the branched polymerization studies suggested that the degree of branching in the resulting polymers increased as the amount of NaI increased, and the majority of the branching occurred during the last stage of the polymerization. The current work should provide a simple procedure for the synthesis of highly branched polymers from commercially available compounds, and this method could be used for the preparation of various highly branched polymers.