Third-order nonlinear optical (NLO) materials have proven to be beneficial for a wide range of applications. Therefore, a novel third-order nonlinear organic single-crystal 4-Dimethylaminobenzaldehyde 2,4-dinitrophenol (DMBDN) is successfully grown adapting slow evaporation method with good optical characteristics and thermal stability. The crystal structure and lattice parameters of the grown crystal are explored by single-crystal X-ray diffraction (SXRD), and it is found that the DMBDN crystallized in a triclinic structure with the centrosymmetric space group P 1 ¯ . The fundamental vibrational frequencies of particular functional groups present in the titled compound are confirmed by Fourier transform infrared (FTIR) spectrum. Using ultraviolet–visible (UV–Vis) spectral analysis, the generated crystal's optical quality is determined. From the Tauc plot, it is calculated that the optical bandgap is 2.04 eV. Sharp emission peaks are seen in the photoluminescence spectrum, which imply violet and blue emission. From thermogravimetric (TG) and differential thermal analyses (DTA), it is found that the crystal possesses a thermal stability of 125.90 °C. The percentage of hydrogen-bonding interactions is assessed using Hirshfeld surface fingerprint plots. The third-order nonlinear optical characteristics such as susceptibility ( χ (3) ) and absorption coefficient ( β ) of the compound are examined using the conventional Z -scan method with a nanosecond pulsed Nd:YAG laser.