Nose-to-brain drug delivery is an innovative approach that leverages the unique anatomical pathways connecting the nasal cavity to the brain, including the olfactory and trigeminal nerve routes. This method bypasses the blood–brain barrier, enabling direct and efficient transport of therapeutic agents to the central nervous system. It offers significant advantages, such as rapid drug action, reduced systemic side effects, and improved patient compliance through non-invasive administration. This entry summarizes factors affecting the nose-to-brain delivery of drugs and the recent development of nanoparticle-based nose-to-brain delivery.