Green synthesis of NiONPs, CuONPs and NiO/CuO nanocomposite were prepared by using hydrothermal method using Sapthodea campanulata leaf extract, which has been used as a stabilizing agent and reducing agent. Sapthodea Campanulata is widely available in India. The newly synthesized nanocomposites were characterized by various instrumental methods such as UV-vis spectroscopy (UV-vis), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), High Resolution-Transmission Electron microscope (HR-TEM). The nanocomposite shows a granular shape with face-centered cubic structure of CuO and NiO. The nanocomposites were photoactive and can be used efficiently as catalyst for degradation of Methylene blue (MB) under visible light irradiation at various times from 0 to 90 min. The percentage of degradation of efficiency was found to be 85%, 92%, 96% for NiO, CuO and NiO/CuO respectively. The higher MB degradation efficiency was exhibited by NiO/CuO nanocomposites (96%). The photocatalytic degradation of MB is based on a pseudo-first-order kinetic model and kinetic rate constant is higher for NiO/CuO nanocomposite (0.0884 min-1) than CuONPs (0.054 min-1) and NiONPs (0.0234 min-1). NiO/CuO nanocomposite proved a good photocatalyst and better stability for eliminating pollution in water. Using an agar well diffusion technique, CuO/NiO nanocomposite was recorded better anti-bacterial activities against both Zone of (E.coli for 20 mm) and (S.aureus for 18 mm) bacteria than ZnONPs and CuONPs.