α-Keton sulfides are versatile building blocks in organic synthesis. From thioic acids and alkenes, we were able to develop the direct synthesis of α-keton thiol esters via photocatalytic oxidative radical additions. This reaction well matches the idea of green chemistry. It takes the advantage of thioxanthone as an inexpensive organic photocatalyst, O2 as a green oxidant, EtOAc as a green solvent, and visible light as a sustainable energy source, and the only byproduct is water.