Herein, we report the nickel-catalyzed denitrogenative cyclization reaction of 1,2,3,4-benzothiatriazine-1,1-dioxides with arynes to generate the polysubstituted biaryl sultams with tolerance of a wide diversity of substituents on every subunit. The mechanistic study indicates that the reaction is initiated by the formation of a diradical species, which reacts with a nickel complex to form a nickelacycle intermediate and carries out the subsequent cyclization through insertion of an aryne.