Accumulating evidence suggests an association between Helicobacter pylori infection and liver diseases; however, it remains unclear whether H. pylori or its extracellular products directly influence hepatocellular carcinoma (HCC) biology. Here, we examined the effects of viable H. pylori, sterile H. pylori-conditioned supernatant (Hp-CS), and isolated H. pylori-derived outer membrane vesicles (Hp-OMVs) on HCC cells. H. pylori adhered to and invaded Huh7 and Hepa1-6 cells, increased Cyclin D1 expression, and enhanced the growth of tumors derived from bacteria-exposed Hepa1-6 cells in immunocompetent C57BL/6J mice. Hp-CS increased HCC cell metabolic activity, colony formation, migration, and invasion. Hp-OMVs were characterized by transmission electron microscopy and nanoparticle tracking analysis. Exposure to Hp-OMVs increased HCC cell metabolic activity, colony formation, cell-cycle progression, and tumor growth in a syngeneic mouse model. Hp-OMVs also increased PI3K, AKT, and mTOR phosphorylation and elevated Cyclin D1 expression. The PI3K inhibitor LY294002 attenuated these molecular changes and reduced Hp-OMV-induced cell-cycle progression and colony formation. These findings show that H. pylori and its extracellular products promote proliferation-associated phenotypes in experimental HCC models. Hp-OMVs are biologically active extracellular components of H. pylori, and pharmacological inhibition supports the involvement of PI3K/AKT/mTOR signaling and Cyclin D1 upregulation in their growth-promoting effects.