An efficient and convenient copper-catalyzed chalcogenation of imidazoheterocycles with sulfur/selenium powder and coumarinyl triflates has been described. This procedure provides a wide range of structurally diverse coumarinylthio-/coumarinylseleno-substituted imidazoheterocycles in good yields and with good functional group tolerance. Biological evaluation showed that the newly synthesized compound 6d possesses significant in vitro antiproliferative activities against human-derived esophageal, breast, stomach, and prostate cancer cell lines compared with the positive control, 5-fluorouracil.