In the areas where viral infections are more common, the incidence of hepatocellular carcinoma (HCC) has declined. This is largely attributed to the availability of vaccines against hepatitis B virus (HBV), antiviral treatments, and a change in diet with healthier foods. However, in the Western world, the HCC incidence rate has risen steadily, probably due to an increased prevalence of metabolic dysfunction-associated fatty liver disease (MAFLD), a condition that has increasingly been considered an important risk factor for HCC. Despite this, in 2019, 41% of HCC cases were diagnosed globally and a majority of diagnosed cases from mainland China were related to HBV. Some HCC cases tested negative for hepatitis B surface antigen (HBsAg) but tested positive for HBV-DNA in blood. This is considered an occult HBV infection (OBI). OBI is related to various mutations in the viral genome, which modifies host immunity, subsequently leading to the long-term persistence of cccDNA in the nucleus of infected hepatocytes. Many OBIs are associated with HBV variants carrying mutations in preS/S genomic regions, which occur either spontaneously or as a result of antiviral treatments. OBIs are also frequently reported in HBV-vaccinated individuals. HBV variants post-HBV vaccination carry mutations in the preS area. This review discusses the relationship between preS variant-related OBIs and the development of HCC in the context of a high-fat diet, one of the preventable behavioral risk factors for MAFLD.