Aerobic photochemistry is a rapidly advancing field that provides sustainable solutions for traditional transformations. In this study, 3H-phenothiazin-3-one is identified as a photocatalyst for the photochemical oxidation of sulfides to sulfoxides. This new photocatalytic method uses a low catalyst loading (0.05 mol%), molecular oxygen as the sole oxidant, and a blue LED lamp as the irradiation source. It can be applied to the oxidation of both alkyl-aryl and alkyl-alkyl sulfides. Moreover, the method is also applicable in the synthesis of the known pharmaceutically active compounds Modafinil and Sulforaphane.