<p>Nanotechnology has displayed widespread application across various sectors due to the unique properties of nanomaterials, particularly nanoparticles (NPs). Tin dioxide (SnO₂) semiconductors have garnered significant attention for their exceptional electrical, optical, and biological properties, which differ considerably from their bulk counterparts due to quantum confinement effects. This review focuses on the biomedical applications of SnO₂ NPs, highlighting their roles in antibacterial, antioxidant, and antifungal activities. The enhanced antibacterial efficacy of SnO₂, especially when doped with transition metals, is attributed to its ability to generate reactive oxygen species that disrupt bacterial cell membranes. The review also discusses the mechanisms underlying these activities, the influence of doping and synthesis methods on the properties of SnO₂, and the potential of SnO₂ NPs in drug delivery, biosensing, and tumor targeting. Although SnO₂ demonstrates significant potential in nanomedicine, challenges such as optimizing biocompatibility and stability still remain. The article concludes by proposing future directions for developing and applying SnO₂-based nanomaterials in biomedical fields.</p>