The detailed mechanisms of Ni-catalyzed ligand-controlled cyclization/cross-coupling of o -bromobenzenesulfonyl acrylamide ( 1a ) with trifluoromethyl alkene were investigated by DFT calculations. The computational results support a single-electron reduction of Ni II precatalyst to give BrNi I L species, which would react with 1a via oxidative addition to afford the (Ar)Ni III LBr 2 complex. The subsequent cyclizations did not proceed until (Ar)Ni III LBr 2 was reduced to the key (Ar)Ni I L complex. For the bpy-involving reaction, the subsequent steps include nucleophilic attack to the carbonyl carbon atom, N-C bond breaking, intramolecular migratory insertion, as well as concerted C-C cross-coupling and β-F elimination. While the ligand of terpyridine promotes the 7-endocyclization followed by stepwise migratory insertion and β-F elimination to afford 2-benzazepine 2,5-dione. For both reactions, a theoretical study implied that the most favorable mechanism involved a Ni I -Ni III -Ni I catalytic cycle. The origins of the chemoselectivity, coupled with the factors responsible, were addressed.