Carotid plaque-derived small extracellular vesicles (psEVs) offer insights into tissue- and disease-specific pathobiology, but their roles in plaque vulnerability and their diagnostic potential remain unclear. Herein, we isolated psEVs from stable and vulnerable (intraplaque hemorrhage [IPH] or fibrous cap rupture [FCR]) plaques in patients with asymptomatic carotid artery stenosis (aCAS). Our findings demonstrated that psEVs alone were sufficient to induce inflammatory endothelial dysfunction in vitro and exacerbate atherogenesis in ApoE-deficient mice. MicroRNA sequencing of psEVs (sequencing cohort, n = 18) identified 21 differentially expressed microRNAs (DEmiRNAs) distinguishing stable and vulnerable plaques, and 41 DEmiRNAs differentiating IPH from FCR subtypes. Subsequent validation using qRT-PCR and the High-throughput nano-bio chip integrated system for liquid biopsy system revealed that plasma-derived sEV miR-497-5p, miR-152-3p, and miR-204-5p effectively differentiated stable plaques from vulnerable plaques, while miR-23a-3p and miR-143-5p further distinguished IPH from FCR subtypes, in both the discovery cohort (n = 178) and an independent external cohort (n = 82). Mechanistic investigations identified miR-497-5p as a key mediator of vulnerable psEVs' proinflammatory and proatherogenic effects through directly targeting atheroprotective uncoupling protein 2 (UCP2). These findings highlight the roles of psEVs in atherogenesis and plaque vulnerability, providing valuable insights for risk stratification and therapeutic decision-making in aCAS patients.