Abstract: Sepsis is a life-threatening multiple organ dysfunction syndrome caused by the dysregulation of the host's immune-inflammatory response to infection. Elevated serum lactate levels are regarded as biomarkers of tissue hypoperfusion and anaerobic metabolism. Sepsis patients often present with hyperlactatemia, which is clinically used to assess disease severity and prognosis. Recent studies have shown that lactate is not only an end-product of metabolism but also serves as a crucial immunometabolic regulatory molecule, playing multiple roles in the pathological process of sepsis. This article aimed to integrate basic and clinical evidence to elucidate the role transformation of lactate from a traditional perfusion marker to a functional immunometabolic mediator, providing a new perspective for the precise assessment and intervention of sepsis.