The current investigation involved the preparation of Iron (II, III) oxide nanoparticles (Fe3O4 NPs) and iron (II, III) oxide nanoparticles coated with 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) ionic liquid (Fe3O4-[BMIM][BF4] NPs) using co-precipitation method. These nanoparticles were analysed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), ultraviolet (UV) spectroscopy, and transmission electron microscopy (TEM). The Fe3O4-[BMIM][BF4] NPs that were obtained exhibited a hexagonal crystal structure. Average crystallite size was calculated from XRD analysis such as Fe3O4 NPs was 15.3 nm, while the Fe3O4-[BMIM] [BF4] NPs had an average size of 5.67 nm. The present study examined the application potential of produced nanoparticles for their antibacterial and anti-cancer activities using both the agar well diffusion method and the MTT assay, respectively. Out of the various types of microbial pathogens tested, the material showed the strongest ability to inhibit the growth of Aspergillus favus (9mm) and Candida Albicans (9mm) at a concentration 80 µg/ml. Additionally, the sample was also examined for its potential to combat breast cancer cells (MCF7) using the MTT assay. The observed cytotoxic effect exhibited a direct correlation with the concentration of the substance. The synthesized Fe3O4-[BMIM] [BF4] nanoparticles have the potential for use in environmental and biomedical applications.