Nanotechnology has emerged as one of the most transformative innovations in modern medicine, offering unprecedented opportunities for disease diagnosis, drug delivery, imaging, tissue engineering, and regenerative medicine. By manipulating materials at the nanoscale level (1–100 nanometers), nanotechnology enables precise interactions with biological systems, improving therapeutic efficacy while minimizing adverse effects. Nanomedicine has demonstrated significant potential in oncology, cardiovascular medicine, infectious disease management, neurology, and personalized healthcare. Advanced nanomaterials such as nanoparticles, liposomes, dendrimers, quantum dots, and nanofibers are increasingly being integrated into clinical practice. This review explores the principles of nanotechnology, current medical applications, advantages, limitations, ethical considerations, and future directions. The findings suggest that nanotechnology will play a critical role in shaping next-generation healthcare systems and precision medicine.