Signal transducer and activator of transcription-6 (STAT6) is highly expressed in various human cancers and considered a regulator of multiple biological processes in cancers, including cell apoptosis. Evidence has indicated that STAT6 predicts a worse prognosis in hepatocellular carcinoma (HCC) patients. The objective of this study was to investigate the effects and mechanism of STAT6 in human HCC cells. We found that STAT6 silencing significantly inhibited HepG2 and Hep3B cell survival and proliferation. We observed that depletion of STAT6 increased HepG2 and Hep3B cell apoptosis by using a histone DNA ELISA detection kit. STAT6 silencing induced expression of apoptosis-associated genes Bax and caspase-3/7 and inhibited anti-apoptosis gene Bcl-2 levels. We also observed that STAT6 silencing downregulated the expression of receptor activator of NF-κB ligand (RANKL). Our results demonstrated that treatment with pcDNA3.1-RANKL abolished STAT6 depletion-induced HepG2 and Hep3B cell apoptosis and growth inhibition. Based on these findings, we believe that RANKL plays a major role in STAT6-induced HCC cell apoptosis.