The Fe3O4/CuO/Chitosan (Fe3O4/CuO/CS) nanocomposite was synthesized from Fe3O4 nanoparticles, CuO nanoparticles and Chitosan using ultrasound assisted method. The Fe3O4 nanoparticles were prepared by co-precipitation method. The CuO nanoparticles were green-synthesized by the assistance of Mangosteen extract. The final nanocomposite was charaterized using X-ray powder diffraction (XRD), field emission scanning electron microscopy (FeSEM), fourier transform infrared (FT-IR) and vibrating sample magnetometer (VSM) techniques. The antibacterial efficacy of the Fe3O4/CuO/CSnanocomposites was tested against Saccharomyces cerevisiae along with gram-positive (Bacillus subtilis) and gram-negative (Escherichia coli) bacteria using the disc diffusion method and determined the minimum inhibitory concentration (MIC)