The elongation of long-chain fatty acids family member 6 (Elovl6) is a key enzyme in lipogenesis that catalyzes the elongation of saturated and monounsaturated fatty acids. Insulin resistance involves upregulation of Elovl6, which has been linked to obesity-related malignancies, including hepatocellular carcinoma (HCC). However, the role of Elovl6 in cancer progression remains unknown. In this study, we analyzed the expression of Elovl6 in 61 clinical HCC specimens. Patients with Elovl6 high-expressing tumors were associated with shorter disease-free survival and overall survival compared to those with Elovl6 low-expressing tumors. Knockdown of Elovl6 in HCC cells reduced cell proliferation and Akt activation, as well as sensitivity to fatty acids. Inhibition of Elovl6 reduced tumor growth and prolonged survival in mice bearing tumors. Taken together, our results indicate that Elovl6 enhances oncogenic activity in liver cancer and is associated with poor prognosis in patients with HCC. Elovl6 may be a therapeutic target for HCC; thus, further studies to confirm this strategy are warranted.