In the title compound, C(21)H(20)N(2)O(3), the naphthalimide unit is almost planar (r.m.s. deviation for the 15 non-H atoms = 0.059 Å). The carboximide N atom and the five C atoms of the 2-methyl-prop-2-enoyl substituent also lie in a plane (r.m.s. deviation = 0.009 Å), which subtends an angle of 84.34 (7)° to the naphthalamide plane. This orients the =CH(2) group of the vinyl fragment towards the naphthalimide rings, giving the mol-ecule an extended configuration. The piperidine ring adopts a chair conformation and there is evidence for some delocalization between the naphthalene and piperidine units, the C-N(pip) bond length being 1.404 (4) Å. In the crystal structure, π-π contacts with centroid-centroid distances of 3.5351 (18) and 3.7794 (18) Å supported by C-H⋯O hydrogen bonds link adjacent mol-ecules in a head-to-tail fashion, forming dimers. These are further stabilized by other C-H⋯O contacts of varying strength, which stack the mol-ecules down the b axis.