Treatment of alkylarenes with N‐bromosuccinimide in a mixture of ethyl acetate and water at 60 °C, a mixture of acetonitrile and water at 80 °C, or a mixture of diethyl carbonate and water under irradiation with a tungsten lamp, followed by a reaction with thioureas or arenethioamides provided the corresponding 2‐amino‐ 4‐arylthiazoles or 2,4‐diarylthiazoles in good to moderate yields, respectively, in one pot. The present reaction is an efficient one‐pot transformation method of alkylarenes into 2‐amino‐4‐arylthiazoles and 2,4‐diarylthiazoles directly under mild and transition‐metal‐free conditions.