Cyclometalated (ppy)Pt^II complexes (ppy = 2-phenylpyridinato-C²,N) catalyze the intramolecular cyclization of aryl propynoates to form coumarins and benzocoumarins. The complex [(ppy)PtCl(MeCN)] (5 mol %) was the most active and efficient catalyst for such reaction, especially in the presence of AgSbF₆ (15 mol %) in 1,2-dichloroethane. With this catalytic system, a wide range of substituents and functional groups proved compatible with the cyclization process, leading to a large variety of substituted coumarins and benzocoumarins (22 examples, 77–99%)