Abstract: Abstract: Chronic hepatitis B (CHB) and metabolic dysfunction-associated steatotic liver disease (MASLD) are the two most prevalent chronic liver diseases worldwide, both of which can progress to end-stage liver disease, including cirrhosis and hepatocellular carcinoma. The coexistence of CHB and MASLD has become a notable feature and emerging trend in hepatology; however, the mechanisms underlying this comorbidity remain incompletely understood. Based on current evidence, this review proposes that the pathogenesis of CHB – MASLD coexistence primarily involves HBx protein, insulin resistance, lipotoxicity, immune dysregulation, and mitochondrial dysfunction. In addition, autophagy, genetic susceptibility, iron overload, metabolic –apoptotic crosstalk, and endoplasmic reticulum stress may also exert potential regulatory roles in this process. This article systematically reviews current research progress on the aforementioned mechanisms, aiming to provide novel insights for disease surveillance, clinical management, and the identification of potential therapeutic targets.