The atom transfer radical polymerization of styrene (St) in bulk using 1‐(chloromethyl)naphthalene (1‐CMN) as an initiator in the presence of CuCl/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) was investigated at 125°C. The results showed that 1‐CMN was an effective initiator with higher initiation efficiency in ATRP of St. The molecular weights of the obtained polystyrene (PS) increased linearly with monomer conversion and the corresponding polydispersity index of polymers remained relatively narrow (1.17–1.30), indicative of well controlled polymerization of St in the presence of 1‐CMN/CuCl/PMDETA. The end functionalized PS with naphthalene‐label exhibited fluorescence in N,N‐dimethylformamide (DMF).