Mesoporous silica nanoparticles (MSNs) have gained wide attention for their role in biomedicine and as drug delivery vehicles. Their structural tunability, high surface area, and easy functionalization impart significant advantages over conventional materials. In this Review, recent advances in the synthesis, drug delivery, and therapeutic roles of MSNs in the treatment of various neurodegenerative and neuroinflammatory diseases are presented. The intention is to understand how MSN formulations that are capable of encapsulating drug molecules can enhance drug delivery by overcoming the blood–brain barrier (BBB) mediated by specific transport processes. The composition and characteristics of the BBB, and how alterations are observed in neurodegenerative diseases including Alzheimer's, epilepsy, and intracerebral hemorrhage are reviewed. Finally, the factors affecting efficient delivery of MSNs into the brain are summarized, and their most promising functional outcomes are discussed.