The blood-brain barrier ( BBB) plays a critical role in maintaining brain homeostasis. BBB dysfunction is closely associated with various neurodegenerative diseases and acute brain injuries, which impair brain defense mechanisms and can exacerbate the progression of pathological conditions. Nitric oxide (NO), an important biological signaling molecule, exerts a wide range of effects on the central nervous system, influencing both physiological and pathological states. This review summarizes the production and metabolism of NO and their effects on BBB permeability, followed by an introduction to the role of NO in pathological conditions such as cerebral ischemiareperfusion injury, neurodegenerative diseases, and brain tumors. NO regulates BBB integrity through the regulation of tight junction proteins and vascular endothelial growth factor receptor 2 (VEGFR2). The review also delves into the potential of NO as a therapeutic target in drug delivery and gene therapy, and explores its potential to enhance drug penetration across the BBB. These explorations provide novel perspectives for future therapeutic strategies.