In the title salt, C19H18NO2+·C7H7SO3, the C=C double bond in the cation has an E configuration. The cation is not planar as the dihedral angle between the quinolinium and benzene ring systems is 14.74 (8)°. The anion is aligned approximately perpendicularly to the cation, with the benzene ring of the anion making dihedral angles of 89.98 (8) and 75.36 (10)° with the quinolinium and benzene ring systems of the cation, respectively. An intramolecular O—H...O hydrogen bond between the hydroxy and methoxy groups generates an S(5) ring motif. The cations link with anions through weak C—H...O interaction into cation–anion pairs along the b direction, and the adjacent pairs are further linked by O—H...O hydrogen bonds and weak C—H...O interactions into a three-dimensional network. The crystal is further stabilized by C—H...π interactions, and π–π interactions [centroid–centroid distances of 3.5236 (12) and 3.5337 (12) Å] are also observed.