Recently, transition-metal-catalyzed C-H functionalization has attracted tremendous interest as a valuable tool for carbon-carbon and carbon-heteroatom bond formation. However, due to the inertness of C(sp 3)-H bonds and the difficulty to achieving high selectivity among the many chemically similar entities in a given molecule, the selective activation of C(sp 3)-H bonds remains a great challenge. The recent progress in transition-metal-catalyzed arylation of unactivated C(sp 3)-H bonds assisted by bidentate directing groups is reviewed, including the scope of reactions, mechanism and synthetic applications.