<p>Herein, we present a versatile, metal-free protocol for arene C-H functionalization through arylsulfonium salts. A key discovery is that simple halogen anions (iodine, bromine) can act as electron donors when combined with arylsulfonium salts, forming electron donor-acceptor complexes that generate aryl radicals upon visible light irradiation. This method enables the late-stage modification of complex bioactive and pharmaceutical compounds, facilitating arene iodination, bromination, phosphonylation, and arylation, which are challenging to achieve with comparable selectivity, diversity, and practicality using other approaches. Notably, the one-pot protocol for arene C-H iodination and C(sp²)-C(sp³) bond formation, along with successful gram-scale iodination and phosphonylation of boscalid, highlights the scalability and practical utility of this strategy.</p>