A visible-light-promoted electron-donor–acceptor (EDA) complex-initiated [5 + 1] annulation between biguanides and perfluoroalkyl halides for the construction of perfluoroalkyl-s-triazines has been developed. It was found that both visible light and dioxygen in the air are favorable for the reaction. A radical–polar crossover mechanism was proposed, in which sequential SET, radical combination, HF