Nanoparticles are one of the innovative drug delivery systems, particularly valuable for the targeted delivery of orphan drugs in rare diseases. Their nanoscale size and large surface area to volume ratio allow for enhanced interaction with biological systems, providing a platform for efficient drug loading and controlled release. Lipid-based nanoparticles, such as liposomes and solid lipid nanoparticles, offer biocompatibility and stability, ensuring sustained and targeted delivery with minimal toxicity. Polymeric nanoparticles, including dendrimers, enable the solubilization of hydrophobic drugs and precise control over drug release. Inorganic nanoparticles, like gold and silica nanoparticles, provide versatility in functionalization and targeted delivery, enhancing therapeutic efficacy. These systems significantly reduce systemic side effects and improve the therapeutic index of orphan drugs, the drugs that are used to treat the rare diseases. Their ability to protect drugs from degradation ensures stability and prolonged activity, making them particularly suitable for complex and chronic conditions associated with rare diseases. Overall, nanoparticle-based drug delivery systems represent a transformative approach in the treatment of rare diseases, offering precise, controlled, and safe delivery of therapeutics, thereby improving patient outcomes and quality of life.