The aim of this study was to identify potential downstream effectors of the oncogene DJ-1 in hepatocellular carcinoma (HCC) cell lines, and examine its role in the Akt signaling pathway and HCC oncogenesis. Expression of the DJ-1 protein was assessed by immunoblotting in several human HCC cell lines. Knockdown of DJ-1 was achieved by transfecting DJ-1-specific short hairpin RNAs into the HepG2 HCC cell line. The effect of DJ-1 downregulation on phosphatase and tensin homolog (PTEN) and phosphorylated Akt was evaluated. In addition, cell cycle, proliferation, adhesion and invasion were analyzed in the DJ-1 knockdown of HepG2 cells. The growth of HepG2-induced tumor was evaluated in a nude mouse model after DJ-1 silencing. Stable DJ-1 knockdown was achieved in HepG2 cells using a shRNA eukaryotic expression vector. Downregulation of DJ-1 increased PTEN expression but decreased phosphorylation of Akt in HepG2 cells. In addition, DJ-1 knockdown resulted in the decreased proliferation, adhesion and invasion of HepG2 cells in vitro, and inhibited the growth of HepG2-induced tumor in vivo. DJ-1 knockdown altered the malignant behavior of HepG2 cells, potentially through the Akt signaling pathway, suggesting a crucial role for DJ-1 in the oncogenesis of HCC.