Hepatitis B virus (HBV) RNA, as a novel biomarker, not only participates in viral replication and infection processes but may also promote the formation of hepatocellular carcinoma (HCC) by influencing hepatocyte proliferation, apoptosis, and the liver microenvironment. However, the specific mechanisms of HBV RNA remain inadequately summarized and thoroughly explored. This article systematically reviews the biological characteristics of HBV RNA and its mechanisms and applications in HCC, aiming to provide a foundation for future research and clinical diagnosis and treatment in HCC.