<p>A nanomaterial is a material that is made extremely small, usually between 1 and 100&#xa0;nm in size or may have at least one part of it in that tiny range. Nano is derived from a Greek word that signifies very tiny or minute. The paper provides a detailed explanation of how the iron-oxide based nanomaterials are synthesised using both top-down and bottom-up methods. Physical methods used in the top-down approach include gas phase deposition, electron beam lithography, pulsed laser ablation, and laser-induced pyrolysis. In contrast to top-down method, bottom-up chemical method consists of processes such as chemical co-precipitation, thermal decomposition, and microemulsion techniques. The characterization of the IONPs can be done by various techniques such as FTIR and UV–visible spectroscopy. The FTIR and UV–visible spectroscopy can be used for the analysis of optical and chemical properties. XRD is used for the examination of crystal structure of IONPs, EDX for the element composition. The DLS is used for the particle size distribution examination. The modern tools used to study surface morphology and nanoscale structure are SEM, TEM and AFM. The paper discusses the diverse biomedical uses of iron oxide-based nanoparticles, particularly their roles as contrast agents in MRI, carriers in targeted drug delivery, and therapeutic tools in cancer treatment via magnetic hyperthermia. These nanoparticles have demonstrated promising efficacy against several cancer types, such as breast, bladder, prostate, pancreatic, gastric, and brain cancer.</p>