Magnetic nanoparticlesMagnetic nanoparticles with surface modifications have attracted considerable attention as a versatile tool in drug deliveryDrug delivery systems due to their exclusive combination of magnetic characteristics and the ability to be modified with specific functional groups. Typically made up of magnetic materials such as oxides of iron, these nanoparticles are tailored on their surface with various ligandsLigands, polymersPolymers, or antibodiesAntibodies to enhance their stability, bioavailability, and capacity for drug loading. The functionalizationFunctionalization process not only improves biocompatibilityBiocompatibility but also allows for the binding of medical substances such as peptidesPeptides, nucleic acids, or minor molecules, facilitating controlled and sustained drug liberation. A key benefit of using magnetic nanoparticlesMagnetic nanoparticles for targeted drug transport is their capability to be directed toward specific tissues or organs through an external magnetic field. This targeted approach significantly reduces systemic toxicityToxicity and minimizes off-target effects commonly related to conventional drug deliveryDrug delivery methods. In addition, the applied magnetic field can improve the nanoparticles’ ability to penetrate physiological barriers, such as the blood–brain barrierBlood-brain barrier, making it possible to target diseases that were challenging to manage before. This chapter provides a detailed analysis of the role of functionalized magnetic nanomaterials (FMNsFunctionalized Magnetic Nanomaterials (FMNs)) in drug deliveryDrug delivery, focusing on their capacity to transport and release therapeutic agents at targeted sites within the body. Key topics include controlled releaseControlled release mechanisms, biocompatibilityBiocompatibility considerations, and real-world case studies, highlighting the potential of FMNsFunctionalized Magnetic Nanomaterials (FMNs) in advancing precision medicinePrecision medicine and improving therapeutic outcomes.