<p>This comprehensive review provides an overview of recent research on the synthesis, physicochemical characterization, and applications of iron oxide (Fe₃O₄) nanocomposites. It emphasizes the advancements in utilizing these nanocomposites for MRI and cancer treatment over the past few decades. The non-uniform size distribution of these nanocomposites enhances their performance over conventional composites, making them highly promising for bioimaging applications. The review covers key applications such as theranostics, gene delivery, biosensing, cell separation, bioprocessing, and catalysis. It also discusses emerging trends and future prospects of advanced iron oxide nanocomposites, along with diverse synthesis and modification strategies employed to tailor their size, morphology, and functional properties. The study focuses on the use of Fe₃O₄ nanoparticles as contrast agents in bioimaging and therapeutic agents for cancer treatment via hyperthermia. The formation and properties of iron oxide nanoparticles have been extensively characterized in the literature such as UV-Visible spectroscopy, FE-SEM, TEM, and FTIR, providing insights into their structural, magnetic, and surface-functional features, revealing nanoparticle sizes ranging from 20 to 90&#xa0;nm and the presence of Fe-O bonds. This review aims to guide researchers in developing innovative iron oxide nanocomposite materials for enhanced bioimaging applications.</p> Graphical Abstract <p></p>