In this paper, synthesis, characterization and examination of antibacterial and anticancer activities of MoS_2/MnMoO_4 nanocomposite have been studied. The nanocomposite was synthesized by a simple one-pot hydrothermal method and then its structural, optical, and magnetic properties were studied by various analyses including X-ray diffraction analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy and vibrating sample magnetometry. To study the antibacterial activity, two Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, as well as for examination of anti-cancer activity, the human colon cancer cell line (HCT-116) have been used. The obtained results show that the nanocomposite was synthesized without any impurities and in the nanosheet morphology. Also, it illustrates a remarkable antibacterial activity for gram-positive bacteria and has no antibacterial effect on gram-negative ones. MIC50 is 51.81 μg/mL for S. aureus bacteria. Additionally, the study of the anti-cancer effect on the HTC-116 cell line shows that it does not have significant anti-cancer activity and IC50 is around 200 μg/mL.