Chronic hepatitis B virus (HBV) infection is one of the leading causes of hepatocellular carcinoma (HCC). The HBV genome is prone to mutate and several variants are closely related to the malignant transformation of liver disease. G1896A mutation (G to A mutation at nucleotide 1896) is one of the most frequently observed mutations in the precore region of HBV, which prevents HBeAg expression and is strongly associated with HCC. However, the mechanisms by which this mutation causes HCC are unclear. Here, we explored the function and molecular mechanisms of the G1896A mutation during HBV-associated HCC. G1896A mutation remarkably enhanced the HBV replication in vitro. Moreover, it increased tumor formation and inhibited apoptosis of hepatoma cells, and decreased the sensitivity of HCC to sorafenib. Mechanistically, the G1896A mutation could activate ERK/MAPK pathway to enhanced sorafenib resistance in HCC cells and augmented cell survival and growth. Collectively, our study demonstrates for the first time that the G1896A mutation has a dual regulatory role in exacerbating HCC severity and sheds some light on the treatment of G1896A mutation-associated HCC patients.