Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Major causes of HCC include hepatitis B and C viral infections, alcoholic hepatitis, and liver cirrhosis. Additionally, conditions such as obesity, diabetes, and metabolic syndrome have been identified as contributing factors to HCC development. In recent years, research on gut microbiota has expanded significantly, resulting in numerous studies exploring the relationship between HCC and gut microbiota. Thus, in this review, we highlight the association between gut microbiota and HCC, focusing on microbiota-related proliferation, inhibition, diagnosis, and immunotherapy. The gut microbiota is proposed to play a crucial role in both the diagnosis and treatment of HCC, paving the way for the development of novel diagnostic and therapeutic approaches for this disease.