This study aims to synthesize and characterize iron oxide nanoparticlesand evaluate them for anti-microbial and anti-oxidant activity. Iron oxide nanoparticles were also modified by precipitation with calcium carbonate particles and their therapeutic activity was assessed. Iron oxide nanoparticles were prepared andanalyzed using TEM, XRD, and Zeta Potential measurements. The synthesized iron oxide nanoparticles were analyzed by TEM images, andthe particles werefound to be in ultra-small size of 5-10 nm. XRD and IR Spectroscopy confirmed the formation of the nanoparticle and the zeta potential of -32.6 indicated that the formed particles were stable. Furthermore, the evaluation of antimicrobial and antioxidant activity was done using the agar diffusion method and the DPPH method respectively. The results indicate that the iron oxide nanoparticles possess good antibacterial activity and antioxidant activity.The iron oxide nanoparticles and modified iron oxide nanoparticles showed moderate inhibitory activity against Staphylococcus aureus (MTCC 87) at1000 μg.According to theantioxidant studies, the modified iron oxide had the highest scavenging activity for DPPH when compared to iron oxide nanoparticles (IC5078.2 μg/ml and (IC5087.5 μg/ml respectively).Thus, Iron oxide nanoparticles and modified particles were synthesized, characterized, and found to be promising anti-oxidant and anti-antimicrobial activity, paving the way to fight antibiotic resistance and also deadlier diseases like cancer.