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Hepatitis B virus (HBV) infection remains a major global health burden, with chronic infection leading to severe liver diseases including cirrhosis and hepatocellular carcinoma (HCC). HBV-encoded X protein (HBx) plays a critical role in viral replication and pathogenesis by modulating host cellular processes, including autophagy and lysosomal function. However, the molecular mechanisms by which HBx disrupts lysosomal biogenesis and autophagic degradation remain elusive. In this study, we show that HBx downregulates the transcription factor EB (TFEB), a master regulator of lysosomal biogenesis, which leading to impaired lysosomal acidification and autophagosome-lysosome fusion. Mechanistically, HBx-mediated TFEB downregulation involves the CUL4A (Cullin 4A)/CUL4B (Cullin 4B)-DDB1 (DNA damage-binding protein 1) E3 ubiquitin ligase complex and is dependent on the DDB1-interacting motif in HBx. HBx mutants defective in DDB1 binding (HBx^R96E and HBx^ΔDBD) fail to downregulate TFEB or impair lysosomal function. Collectively, our findings identify a pathway by which HBx disrupts lysosomal function via CUL4A/CUL4B-DDB1-dependent TFEB downregulation, providing insights into HBV-associated liver pathogenesis and highlighting potential targets for therapeutic intervention.