The study aims to evaluate the third-order optical nonlinearity caused by laser irradiation in transition metal oxide incorporated into graphitic carbon nitrides. The work describes the synthesis of nano-sized hybrid g-C3N4/ZnO (14%) and g-C3N4/CdO (14%). Nano-sized transition metal oxides: ZnO and CdO, have been prepared by thermally decomposing the organic precursors; Zinc Acetate Dihydrate, Cadmium Acetate Dihydrate, and Urea at 873 K. Graphitic carbon nitrides are synthesized from urea, which also functions as a reducing agent. The synthesized sample's structural and morphological characterization are investigated using X-ray diffraction (XRD), Fourier transforms infrared (FTIR), UV-Vis. spectra, field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). The grain size of the ZnO and CdO nanoparticles is observed to be ̴ 21 nm and ̴ 28 nm, respectively. The absorption in the samples is found to be 250-450 nm and transmit the light in the visible spectrum as observed in UV-Vis. spectra. The bandgap values calculated from Tauc’s plot for the hybrid structure of g-C3N4/ZnO and g-C3N4/CdO are found to be 2.97 eV and 2.30 eV. The z-scan method is adopted to evaluate the nonlinear susceptibility (χ3), intensity-dependent absorption coefficient (β), and nonlinear index of refraction (n2) using a pulsed Nd-YAG laser (~ 532 nm). The results of the composite of g-C3N4/ZnO and g-C3N4/CdO show good third-order susceptibility and hence are useful for use as an optical limiter.