Extracellular vesicles (EVs) carry proteins, lipids and nucleic acids that can influence ovarian and systemic metabolic function. This narrative review examines their molecular mechanisms, biomarker potential and experimental therapeutic applications in polyendocrine metabolic ovarian syndrome (PMOS), previously termed polycystic ovary syndrome. Follicular fluid EV cargo varies with disease phenotype and adiposity, but these associations have not established clinically validated diagnostic tests. Follicular fluid collection also requires an invasive procedure and should not be described as a non-invasive screening approach. Experimental studies indicate that selected mesenchymal stromal cell-derived EV preparations can modulate granulosa cell survival, mitochondrial quality control and endocrine function. Adipose stromal cell- and brown adipose tissue-derived preparations additionally affect metabolic pathways, while engineered small EVs can improve delivery of a PI3K agonist in mice. Disease-associated follicular fluid EVs may impair oocyte maturation or promote abnormal granulosa cell proliferation; their effects depend on source, cargo and recipient context. We distinguish PMOS-specific evidence from chemotherapy-related ovarian injury and premature ovarian insufficiency, summarize treatment models, administration and endpoints, and evaluate reporting in selected studies against MISEV2023 recommendations. The evidence remains predominantly preclinical. Incomplete EV characterization, heterogeneous doses and models, limited biodistribution data and uncertain long-term reproductive safety prevent direct extrapolation to patient care.