<p>Polystyrene (PS), a widely used thermoplastic, is valued for its excellent mechanical strength and chemical stability. However, its limited functionality restricts its performance in advanced applications. In this study, a novel and efficient strategy for the direct chemical modification of polystyrene through an enhanced Gomberg-Bachmann-type arylation reaction is presented. Unlike traditional approaches, this method operates under UV light without the need for photosensitizers or metal-based catalysts, offering a cleaner and more sustainable route to polymer functionalization. The reaction proceeds via in situ generation of aryl radicals from aryl diazonium salts in the presence of pyridine, which subsequently attacks the polystyrene backbone to form arylated derivatives. This metal-free, photoinitiated process not only simplifies the reaction conditions but also opens new avenues for tuning the surface properties and chemical reactivity of polystyrene for use in coatings, sensors, and advanced material interfaces.</p>