Neurodegenerative diseases represent a major therapeutic challenge due to the restricted permeability of the blood–brain barrier and the lack of effective drug delivery systems capable of targeting the central nervous system. Exosomes, endogenous extracellular vesicles secreted by virtually all cell types, have emerged as promising biological nanocarriers for therapeutic delivery. These nanoscale vesicles possess inherent biocompatibility, low immunogenicity, and the intrinsic ability to cross biological barriers including the blood–brain barrier. This review provides a comprehensive analysis of exosome-based drug delivery platforms, examining their biogenesis, structural properties, isolation methodologies, engineering strategies, and translational applications in neurodegenerative disorders. We critically evaluate the molecular mechanisms underlying exosome-mediated transport, targeting strategies for neural delivery, and therapeutic applications in Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and multiple sclerosis. Furthermore, we discuss safety considerations, manufacturing challenges, regulatory frameworks, and future directions for clinical translation of exosome-based therapeutics.