Obstructive sleep apnea (OSA) and metabolic syndrome (MetS) are highly comorbid conditions, jointly constituting a significant risk factor for metabolic and cardiovascular diseases. However, their complex bidirectional interactions and the heterogeneity of clinical intervention outcomes cannot be fully explained by a single pathological mechanism. Focusing on the bidirectional relationship between OSA and MetS, this article systematically reviews their key pathological links. This includes obesity as an initiating factor for OSA, and intermittent hypoxia along with sleep structure abnormalities as the core mechanisms by which OSA drives metabolic dysregulation. Moving beyond unidirectional models, the article further explores shared upstream driving mechanisms from the perspectives of aging and systemic inflammation. This review aims to provide a deeper understanding of the integrated pathophysiological network underlying OSA-MetS comorbidity and to offer a novel theoretical framework for exploring comprehensive management strategies targeting their common roots.