A novel Schiff base compound named as phenylmethanaminium (E)-4-((benzylimino)methyl)benzoate C7H10N+center dot C15H12NO2- (A) is synthesized by the chemical reaction of benzylamine and 4-carboxybenzaldehyde in ethanol, and the structure of the titled compound is verified using the single-crystal X-ray diffraction technique. Structural investigation inferred that the crystal packing is mainly stabilized by N-H center dot center dot center dot O and comparatively weak C-H center dot center dot center dot O bonding between the cation and anion and further stabilized by weak C-H center dot center dot center dot pi and C-O center dot center dot center dot pi interactions. Hirshfeld surface analysis is employed to explore the noncovalent interactions that are responsible for crystal packing quantitatively. Furthermore, we have used state-of-the-art quantum chemical calculations to get comprehensive insights into the structure-optoelectronic property relationship for the entitled compound. The molecular geometry of compound A is optimized at the M06/6-311G* level of theory. The linear polarizability, third-order nonlinear optical (NLO) polarizability, total and partial density of states, and UV-visible spectrum are calculated through quantum chemical calculations. We believe that compound A is not only a new addition to crystallographic data but also possesses good optical and NLO properties for its potential use in lasers and frequency-converting applications.