Brain diseases, such as brain tumors, neurodegenerative diseases, cerebrovascular diseases and brain injuries, are caused by various pathophysiological changes such as excessive or impaired angiogenesis, neuroinflammation, immune activation or suppression, neurodegenerative disorders, and neurovirulent protein deposition, which poses a serious health threat. Brain disorders are often difficult to treat due to the presence of the blood‐brain barrier (BBB), which hinders the delivery of drugs to the brain. Biomimetic nanovesicles (BNVs), including endogenous extracellular vesicles (EVs) derived from various cells and artificial nanovesicles (ANVs), possess the ability to penetrate the BBB and thus can be utilized for drug delivery to the brain. BNVs, especially endogenous EVs, are widely distributed in body fluids and usually carry various disease‐related signal molecules such as proteins, RNA and DNA, and may therefore also be analyzed to understand the etiology and pathogenesis of brain diseases. This review will cover the exhaustive classification and characterization of BNVs and pathophysiological roles involved in various brain diseases, and emphatically focus on nanotechnology‐integrated BNVs for brain disease theranostics, including various diagnosis strategies and precise therapeutic regulations (e.g., immunity regulation, disordered protein clearance, anti‐neuroinflammation, neuro‐regeneration, angiogenesis and the gut‐brain axis regulation). We also discuss and outline the remaining challenges and future perspectives regarding the nanotechnology‐integrated BNVs for the diagnosis and treatment of brain diseases.This article is protected by copyright. All rights reserved