We report herein an efficient synthesis of 3‐arylbenzothiazolin‐2‐one compounds. First, substituted benzothiazoles can be smoothly oxidized to benzothiazolin‐2‐one derivatives in the presence of CuCl2 and trifluoroacetic anhydride. Secondly, the Cu2S‐catalyzed N‐arylation of benzothiazolin‐2‐one with arylboronic acids yields a series of novel 3‐aryl benzothiazolin‐2‐one derivatives. The method provides good yields for a variety of substrates and shows good compatibility with functional groups. The usefulness of the skeleton was further illustrated by the derivatization of 3‐aryl‐benzothiazolin‐2‐one. Mechanistic studies suggest that the oxidation of benzothiazole may undergo a free radical reaction process.