In the title compound, C(21)H(23)N(3)O(2), the indolin-2-one group is essentially planar, with a maximum deviation of 0.016 (2) Å for the N atom, and makes a dihedral angle of 84.38 (14)° with the benzene ring. The =N-N(H)-C(=O)-C- torsion angle is 0.9 (3)°. In the crystal, mol-ecules are linked into a three-dimensional network via N-H⋯O and C-H⋯O hydrogen bonds. In addition, a C-H⋯π inter-action was observed.