The review discusses the influence of physicochemical properties of iron oxide nanoparticles (IONPs) on their antibacterial activity. IONPs, due to their unique magnetic and tunable properties, are promising candidates for antimicrobial applications. Their antibacterial activity is influenced by synthesis methods, precursors, size, shape, concentration, and surface modifications. Altering these parameters can affect the production of reactive oxygen species (ROS), which disrupt bacterial cell walls, membranes, and major biomolecules, affecting metabolic processes. The review investigates the antibacterial activity of bare and surface-modified IONPs and the influence of physicochemical parameters on their activity. It also reports the potential mechanisms of IONPs' action in driving antimicrobial activity. Antimicrobial resistance (AMR) is a growing global health concern, prompting the development of alternative antimicrobial agents like IONPs. IONPs exhibit nonspecific antibacterial activity through electrostatic interactions and ROS generation. Their antimicrobial activity is influenced by factors such as synthesis methods, precursors, size, and surface modifications. Surface modification can enhance the antimicrobial activity of IONPs, as coated nanocomplexes show more potent activity than bare IONPs. The review covers various synthesis methods for IONPs, including coprecipitation, sol-gel, hydrothermal, green synthesis, and others. The physicochemical properties of IONPs, such as size, shape, and concentration, significantly influence their antibacterial activity. Smaller IONPs with a higher surface area-to-volume ratio exhibit enhanced antibacterial activity. Spherical-shaped IONPs show higher antibacterial activity compared to hexagonal ones. The concentration of IONPs also affects their antimicrobial activity, with higher concentrations generally leading to greater inhibition zones. The antimicrobial activity of IONPs is influenced by the type of iron salt precursors used in their synthesis. Different precursors can result in varying levels of antibacterial activity. Surface modification with antimicrobial agents like gentamicin, kanamycin, rifampicin, and others enhances the antibacterial activity of IONPs. Additionally, doping IONPs with impurities can increase their antibacterial activity by altering their physicochemical properties and enhancing their interaction with microorganisms. The antibacterial mechanisms of IONPs include cell membrane disruption, ROS production, damage to cellular content, enzyme inactivation, and inhibition of efflux pumps. ROS generated by IONPs cause oxidative stress, leading to cell death. IONPs can also disrupt the bacterial cell membrane, damage DNA and proteins, inhibit enzyme activity, and interfere with efflux pumps, all contributing to their antimicrobial effects. The toxicity of IONPs is a concern, but their potential as antimicrobial agents is significant due to their ability to disrupt bacterial cells and inhibit microbial growth.The review discusses the influence of physicochemical properties of iron oxide nanoparticles (IONPs) on their antibacterial activity. IONPs, due to their unique magnetic and tunable properties, are promising candidates for antimicrobial applications. Their antibacterial activity is influenced by synthesis methods, precursors, size, shape, concentration, and surface modifications. Altering these parameters can affect the production of reactive oxygen species (ROS), which disrupt bacterial cell walls, membranes, and major biomolecules, affecting metabolic processes. The review investigates the antibacterial activity of bare and surface-modified IONPs and the influence of physicochemical parameters on their activity. It also reports the potential mechanisms of IONPs' action in driving antimicrobial activity. Antimicrobial resistance (AMR) is a growing global health concern, prompting the development of alternative antimicrobial agents like IONPs. IONPs exhibit nonspecific antibacterial activity through electrostatic interactions and ROS generation. Their antimicrobial activity is influenced by factors such as synthesis methods, precursors, size, and surface modifications. Surface modification can enhance the antimicrobial activity of IONPs, as coated nanocomplexes show more potent activity than bare IONPs. The review covers various synthesis methods for IONPs, including coprecipitation, sol-gel, hydrothermal, green synthesis, and others. The physicochemical properties of IONPs, such as size, shape, and concentration, significantly influence their antibacterial activity. Smaller IONPs with a higher surface area-to-volume ratio exhibit enhanced antibacterial activity. Spherical-shaped IONPs show higher antibacterial activity compared to hexagonal ones. The concentration of IONPs also affects their antimicrobial activity, with higher concentrations generally leading to greater inhibition zones. The antimicrobial activity of IONPs is influenced by the type of iron salt precursors used in their synthesis. Different precursors can result in varying levels of antibacterial activity. Surface modification with antimicrobial agents like gentamicin, kanamycin, rifampicin, and others enhances the antibacterial activity of IONPs. Additionally, doping IONPs with impurities can increase their antibacterial activity by altering their physicochemical properties and enhancing their interaction with microorganisms. The antibacterial mechanisms of IONPs include cell membrane disruption, ROS production, damage to cellular content, enzyme inactivation, and inhibition of efflux pumps. ROS generated by IONPs cause oxidative stress, leading to cell death. IONPs can also disrupt the bacterial cell membrane, damage DNA and proteins, inhibit enzyme activity, and interfere with efflux pumps, all contributing to their antimicrobial effects. The toxicity of IONPs is a concern, but their potential as antimicrobial agents is significant due to their ability to disrupt bacterial cells and inhibit microbial growth.