Nonalcoholic steatohepatitis (NASH) is becoming the most common cause of hepatocellular carcinoma (HCC). Natural products including edible mushrooms are gaining attention for the prevention and treatment of lifestyle related disorders. Ceraceomyces tessulatus (strain BDM-X) possesses potent antioxidative stress activity. In this study, we hypothesize that BDM-X treatment protects the liver of mouse with NASH by reducing inflammation in a novel NASH-HCC mouse model. C57BL/6J female pups were exposed to low-dose streptozotocin (STZ) and fed a high-fat diet (HFD) 32 from the age of 4 weeks to 16 weeks. Water extract of BDM-X was given at 500 mg/kg dose daily by oral gavage started at the age of 12 weeks and continued until 16 weeks of age along with HFD feeding. We found that BDM-X improved the histopathological changes, serum aminotransferases, and blood glucose levels in NASH mice. The hepatic protein expressions of SIRT1 and IL-10 were significantly repressed in NASH mice. BDM-X treatment restored these expressions. BDM-X treatment effectively reduced the progression of NASH by suppressing the protein expression of SREBPlc, p-NF-κB, Ep-CAM, and prothrombin in the NASH liver. In conclusion, our data suggest that BDM-X can protect the liver against inflammation and lipogenesis in NASH-HCC mice.