Novel materials for biomedical applications are in critical need of time. In the present work, the antibacterial properties of Co Ni Mg FeO nanoparticles (NPs) are assessed by the disc diffusion method for the common pathogen, that is, Gram-negative ( and ) and Gram-positive () bacteria. Overnight grown bacterial cultures were individually lawn-cultured on nutrient agar plates. All samples of NP concentrations (2 mg/mL) were prepared in sterile water and dispensed by sonication. Sterile filter paper discs (1.0 mm) were saturated by the (doped CoFeO) NP solution and incubated at 37 ± 0.1 °C for 24 h. The NPs with a fine size of 30-70 nm of Co Ni Mg FeO were achieved using the sol-gel method by doping CoFeO initially with Ni and codoping with Mg, and their properties were studied by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared techniques. According to the results, CoNiMgFeO NPs exhibited potent antibacterial activities against having an inhibition zone of 6.5 mm and having an inhibition zone of 6 mm as that were examined. The result shows that the bacteriostatic properties of NPs are used for numerous applications such as hyperthermia, antibacterial treatments, and targeted drug delivery.