Recently, many types of research in clay-based nanocomposites have been accomplished to eliminate pollutants from water sources. Nanocomposite materials have advanced properties useful for contaminate removal such as higher surface area, thermal stability, selectivity to remove different contaminants, improved processability, and fast decontamination. This study aimed to verify the efficiency of heterogeneous photocatalysis for the degradation of organic pollutants. In this work we describe a simple and low-cost method for decolorizing malachite green dye wastewaters, using clay-supported CuO NCPs as a photocatalyst. This nanocomposite was synthesized by the co-precipitation method by stirring at 70 oC using copper pentahydrated salt as a precursor. UV-Vis spectrometer (UV-Vis), Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), scanning electron microscopy along with Energy Dispersive X ray spectroscopy (SEM-EDX) were investigated to study materials absorbance, functional group, crystalline size, morphology, and elemental analysis respectively. Photocatalytic degradation of aqueous solution of malachite green dye using as-synthesized photocatalysts was studied under a tungsten bulb light. The higher photocatalytic degradation efficiency of clay-supported CuO NCPs is attributed to the increase in the surface area of a composite and the lower rate of recombination of the photo-generated electrons. The percentage degradation efficiency of malachite green dye was 89.67 using 0.064g of clay-supported CuO NCPs and 20 ppm malachite green dye aqueous solution at a contact time of 180 minutes.