Benzofused lactams, especially indolin‐2‐one and dihydroquinolin‐2‐one are popular structural motives in durgs and natural products. Herein, we developed a room temperature and robust synthesis of benzofused lactams through cobalt(III)‐catalyzed C(sp2)−H amidation. In this protocol, in‐situ formation of Cp*Co(III)(ligand) catalyst from Cp*Co(CO)I2 and ligand simplify the synthetic effort of cobalt