This review article explores the multifunctional applications of iron oxide nanoparticles (MNPs) in biomedical and biotechnological fields, emphasizing their potential in drug delivery systems. MNPs, due to their magnetic properties and biocompatibility, are highly effective in targeted drug delivery, imaging, and therapy. The article discusses the synthesis strategies of MNPs, including chemical, physical, and biological methods, and the surface functionalization techniques that enhance their performance. Key aspects such as saturation magnetization, remanence, and coercivity are highlighted for their role in biomedical targeting mechanisms. The review also covers the magnetic properties of MNPs and their impact on delivery efficiency, particularly in tumor targeting. Finally, the article examines the biomedical applications of MNPs, focusing on drug delivery, cell separation, biomarker development, imaging, and hyperthermia, with a particular emphasis on cancer treatment. Despite some limitations, such as rapid clearance and weak magnetic properties, MNPs remain a promising tool in various therapeutic and diagnostic applications.This review article explores the multifunctional applications of iron oxide nanoparticles (MNPs) in biomedical and biotechnological fields, emphasizing their potential in drug delivery systems. MNPs, due to their magnetic properties and biocompatibility, are highly effective in targeted drug delivery, imaging, and therapy. The article discusses the synthesis strategies of MNPs, including chemical, physical, and biological methods, and the surface functionalization techniques that enhance their performance. Key aspects such as saturation magnetization, remanence, and coercivity are highlighted for their role in biomedical targeting mechanisms. The review also covers the magnetic properties of MNPs and their impact on delivery efficiency, particularly in tumor targeting. Finally, the article examines the biomedical applications of MNPs, focusing on drug delivery, cell separation, biomarker development, imaging, and hyperthermia, with a particular emphasis on cancer treatment. Despite some limitations, such as rapid clearance and weak magnetic properties, MNPs remain a promising tool in various therapeutic and diagnostic applications.