A practical protocol for the direct aminoalkylation of isatins with tetrahydroisoquinolines and other amines via a photoredox catalyzed radical–radical cross-coupling process is described. Various 3-hydroxy-3-aminoalkylindolin-2-ones with eminent diastereoselectivity were efficiently assembled in good to excellent yield under mild conditions, thus providing a facile route to rapidly access 3-substituted-3-hydroxyindolin-2-ones of potential biological importance.