An organic 4-aminopyridine monophthalate (PA4AP) single crystal grown by solvent evaporation at room temperature was studied for third-order nonlinear optical and antibacterial applications. The title material was found to crystallize in a non-centrosymmetric orthorhombic system with space group P212121, and the crystallographic information was acquired by its response to X-ray diffraction analysis. The functional groups and their different modes of vibration were studied by FTIR spectroscopy to identify the various chemical bonds present in PA4AP. Optical absorption study revealed less absorption in the visible region with an absorption cut-off wavelength at 315 nm, below which the material shows complete absorption. The title crystal was characterized for luminescence and based on this the inter-band structures were analysed for crystal defects. Mechanical and dielectric properties with an emphasis on solid-state parameters were investigated to understand the crystal stability for device applications. Kurtz–Perry powder analysis revealed that the PA4AP crystal has comparable second harmonic generation efficiency with the well-known KDP crystal. The third-order nonlinear optical susceptibility (χ(3)), nonlinear absorption coefficient (β) and nonlinear refractive index (n2) of title material were found to be 1.06 × 10−6 (esu), 6.51 × 10−5 (cm W−1) and 2.33 × 10−8 (cm2 W−1), respectively. The reverse saturable absorption observed in open aperture Z-scan indicates the suitability of PA4AP for optical limiting application. The antibacterial activity was investigated against few foodborne pathogens which show the antibacterial stability of PA4AP against Shigella flexneri and Vibrio cholerae bacteria. © 2020, The Minerals, Metals & Materials Society.