The combined experimental and computational spectroscopic calculations were performed to analyze the nonlinear optical property of 7-diethylamino-4-methylcoumarin. The band gap was measured in ten different solvents and found very favorable in dimethyl formamide. The molecular electrostatic potential surface and Hirshfeld’s surfaces were used to determine the reactive sites of the title molecule. Intramolecular interactions were accounted by Mulliken and natural charge distribution, Fukui functions, and fingerprint plots. The electronic transitions were studied by experimental and computed absorption and photoluminescence spectra. Infrared spectroscopy combined with DFT calculation was used to confirm the molecular vibrations related to the chemically active functional groups. The high value of hyperpolarizability showed the enhanced nonlinear optical behavior of the molecule. The Z-Scan plots gave a valley-like shape showing the occurrence of the reverse saturable absorption and the theoretical fit revealed the occurrence of two-photon absorption and the potential application of the molecule to be used for optical limiting applications.