A copper-mediated direct C3 amination of imidazopyridines has been disclosed under additive-free conditions in short reaction times. This methodology utilizes commercially available N-fluorobenzenesulfonimide (NFSI) as the amino source, which exhibits broad substrate scope and good functional group tolerance. The obtained C3-aminated imidazopyridines can undergo further desulfonylation transformations. Control experiments suggest that this reaction probably proceeds via a free-radical mechanism. Moreover, NFSI also shows potential application in C-H fluorination of imidazopyridines.