The di-hydro-quinoxaline ring system of the title mol-ecule, C19H17N3O3, is approximately planar [maximum deviation = 0.050 (2) Å], the dihedral angle between the planes through the two fused rings being 4.75 (8)°. The mean plane through the fused-ring system forms a dihedral angle of 30.72 (5)° with the attached phenyl ring. The mol-ecular conformation is enforced by C-H⋯O hydrogen bonds. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming a three-dimensional network.