Iron oxide nanoparticles (IONPs) have shown great potential in biomedical applications due to their biocompatibility, biodegradability, and low toxicity. They are used in various fields such as magnetic resonance imaging (MRI), targeted drug delivery, cancer immunotherapy, and hyperthermia. However, the clinical application of IONPs is still limited due to the lack of understanding of their biomedical effects and the need for further research on their preparation and applications in different animal models, cell types, and humans. This review summarizes the recent progress in the synthesis of IONPs, their biological interactions in different animal models and cell types, and their clinical applications. The review highlights the importance of IONP size, surface coating, and functional groups in determining their biocompatibility and toxicity. It also discusses the various biomedical applications of IONPs, including their use in cancer treatment, drug delivery, and imaging. The review emphasizes the need for further research to improve the design and application of IONPs in biomedical research and clinical trials. The review also discusses the potential of IONPs in various biomedical applications, including their use in cancer therapy, drug delivery, and imaging. The review concludes that IONPs have a promising future in biomedical applications, but further research is needed to fully understand their potential and improve their safety and effectiveness.Iron oxide nanoparticles (IONPs) have shown great potential in biomedical applications due to their biocompatibility, biodegradability, and low toxicity. They are used in various fields such as magnetic resonance imaging (MRI), targeted drug delivery, cancer immunotherapy, and hyperthermia. However, the clinical application of IONPs is still limited due to the lack of understanding of their biomedical effects and the need for further research on their preparation and applications in different animal models, cell types, and humans. This review summarizes the recent progress in the synthesis of IONPs, their biological interactions in different animal models and cell types, and their clinical applications. The review highlights the importance of IONP size, surface coating, and functional groups in determining their biocompatibility and toxicity. It also discusses the various biomedical applications of IONPs, including their use in cancer treatment, drug delivery, and imaging. The review emphasizes the need for further research to improve the design and application of IONPs in biomedical research and clinical trials. The review also discusses the potential of IONPs in various biomedical applications, including their use in cancer therapy, drug delivery, and imaging. The review concludes that IONPs have a promising future in biomedical applications, but further research is needed to fully understand their potential and improve their safety and effectiveness.