An efficient palladium-catalyzed denitrogenative Suzuki-Miyaura type cross-coupling of 1,2,3-benzotriazin-4(3H)-ones with organoboronic acid is described. The reaction is compatible with various aryl and alkenyl boronic acids affordingortho-arylated and alkenylated benzamides in good to high yields. Heteroaromatic boronic acids were also successfully employed. Along with this, a coupling reaction was established by using phenyl boronate ester as the coupling partner. The reaction is believed to proceedviaa five-membered aza-palladacyclic intermediate. DFT calculations were studied comparing the reactivity of palladium and nickel complexes in the five-membered aza-metallacycle formation from 1,2,3-benzotriazin-4(3H)-ones. The application of the reaction was successfully demonstrated by convertingortho-alkenylated products toortho-alkylated products in high yieldsviaa reduction reaction.