Atmospheric pressure Micro-jet plasma technique is used in this study to create Ag–ZnO core/shell nanoparticles. Several different methods, including X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy (UV–Vis), confirmed the characterization of the synthesized Ag–ZnO core/shell nanoparticles. The pureness of these nanoparticles was validated by XRD analysis, which showed no peaks associated with secondary phases for Ag–ZnO. The synthesis of very pure Ag–ZnO core/shell nanoparticles was also verified by EDX analysis. To understand the high agglomeration rate, the surface morphology was studied by FE-SEM. The Ag–ZnO core/shell nanoparticles were measured to be between 20 and 60[Formula: see text]nm in size by transmission electron microscopy. Ag–ZnO core/shell nanoparticles showed energy band gaps of 3.22[Formula: see text]eV. After that, the antibacterial activity of the prepared nanoparticles was tested against two different types of Gram-positive bacteria [Formula: see text]Staphylococcus. epidermidis and Staphylococcus aureus[Formula: see text] and two different types of Gram-negative bacteria [Formula: see text]Klebsiella. pneumonia and Escherichia coli[Formula: see text] that were isolated from the oral cavity. Additionally, the antifungal activity of the prepared nanoparticles was tested against two different types of yeast [Formula: see text]Candida[Formula: see text]. Antimicrobial activity was shown by the Ag–ZnO nanoparticles produced using the micro-jet plasma method, and the findings suggested that these nanoparticles may be used to eliminate dangerous and harmful bacteria and fungi.