<p>The growing demand for precision oncology has intensified interest in magnetically controlled nanocarriers (MCNCs) as versatile platforms for targeted drug delivery and theranostics. Conventional cancer therapies are often limited by nonspecific drug distribution, systemic toxicity, and poor efficacy against heterogeneous tumors. MCNCs, typically based on superparamagnetic iron oxide nanoparticles and hybrid composites, address these limitations by enabling site-specific accumulation, stimuli-responsive release, and real-time imaging in external magnetic fields. These systems integrate diagnostic and therapeutic functions within a single platform, advancing the concept of image-guided and personalized medicine. Recent advances in surface engineering, biodegradable ferrites, and magnetic–plasmonic hybrids have enhanced their biocompatibility, stability, and multimodal performance. Furthermore, their incorporation into combination therapies, such as magnetic hyperthermia, photothermal therapy, and immunotherapy, has demonstrated synergistic antitumor effects. Despite these advances, translational barriers persist, including challenges in deep tissue targeting, biosafety validation, scalable synthesis, and regulatory standardization. Integrating AI-driven modeling and digital twins can optimize the design, dosing, and magnetic field control for personalized therapy. Collectively, magnetically regulated theranostic nanoplatforms represent a promising frontier in precision cancer medicine, bridging diagnosis, therapy, and real-time monitoring toward safer, more effective, and patient-tailored oncologic care.</p>