The increasing prevalence of antimicrobial resistance has led to a growing need for more potent, selective, and safe antimicrobial agents. Iron oxide nanoparticles (IONPs) due to their unique magnetic and tunable properties, have emerged as promising candidates for various theragnostic applications, including antimicrobial use. The antimicrobial activities of IONPs are influenced by their synthesis methods, precursors, size, shape, concentration, and surface modifications. These parameters can alter the production of reactive oxygen species (ROS), which disrupt bacterial cell walls, membranes, and biomolecules, affecting metabolic processes. This review examines the antibacterial activity of bare and surface-modified IONPs, focusing on the influence of physicochemical parameters and the potential mechanisms of action. The review also discusses the antimicrobial efficacy of IONPs concerning their precursors, manufacturing techniques, size, shape, concentration, and surface modification materials. Additionally, it explores the antimicrobial mechanisms of IONPs, including ROS generation, electrostatic interaction, and disruption of bacterial cell membranes and biomolecules.The increasing prevalence of antimicrobial resistance has led to a growing need for more potent, selective, and safe antimicrobial agents. Iron oxide nanoparticles (IONPs) due to their unique magnetic and tunable properties, have emerged as promising candidates for various theragnostic applications, including antimicrobial use. The antimicrobial activities of IONPs are influenced by their synthesis methods, precursors, size, shape, concentration, and surface modifications. These parameters can alter the production of reactive oxygen species (ROS), which disrupt bacterial cell walls, membranes, and biomolecules, affecting metabolic processes. This review examines the antibacterial activity of bare and surface-modified IONPs, focusing on the influence of physicochemical parameters and the potential mechanisms of action. The review also discusses the antimicrobial efficacy of IONPs concerning their precursors, manufacturing techniques, size, shape, concentration, and surface modification materials. Additionally, it explores the antimicrobial mechanisms of IONPs, including ROS generation, electrostatic interaction, and disruption of bacterial cell membranes and biomolecules.