A copper-catalyzed aerobic 3-hydroxyisoindolinone synthesis was developed via the benzylic double C(sp(3))-H functionalization of 2-alkylbenzamides. In this reaction, molecular oxygen was used as both an oxidant for C(sp(3))-H functionalization and an oxygen source. Our method can be extended to diverse benzylic C(sp(3))-H bonds and shows excellent functional group tolerance.