In the present work, a 3rd-order nonlinear optical compound 3-Aminopyridinium-2‑chloro-4-nitrobenzoate (3AP2C4N) was successfully synthesised by following the slow-cooling solution growth technology 3AP2C4N single crystals are grown. The crystalline structure, established by single crystal x-ray diffraction investigation, revealed that 3AP2C4N belong to the triclinic system with the centro-symmetric space group of P-1. Powder x-ray diffraction measurement results support the formation of crystalline phase. The Fourier transform infrared analysis revealed the existence of different functional groups establishing the formation of 3AP2C4N molecule. Adopting the UV–Vis-NIR spectrometer, the absorption coefficient was measured and the calculated bandgap for 3AP2C4N was 3.25 eV. The luminescence properties of the title compound, which was excited at 320 nm, were studied using photoluminescence spectroscopy. TG-DTA measurements were used to investigate the thermal behaviour of 3AP2C4N. From the Z-scan approach it is evident that 3AP2C4N crystals are much suitable for optical limiting applications. DFT simulations at the B3LYP / 6–311++G (d, p) level enabled to evaluate the molecule's HOMO-LUMO, molecular electrostatic potential and contour map. The Hirshfeld surface investigations showed the presence of intermolecular interactions in the molecule.