2α-Hydroxyeudesma-4,11(13)-dien-8β,12-olide (HEDO), a eudesmane-type sesquiterpene lactone belonging to large group of plant terpenoids isolated from , displays cytotoxic activity against diffuse large B cell lymphoma cells in vitro. However, the molecular mechanism of the anticancer effect remains unclear. In this study, we showed that HEDO inhibits cell growth by inducing apoptosis in lymphoma cell lines through its antiproliferative activity. HEDO increases the depolarization of mitochondrial membrane potential and upregulated intracellular reactive oxygen species (ROS). Furthermore, we examined the cell cycle effect, and our results provided evidence that the arrest of the cell cycle at the SubG0/G1 phase plays an important role in the ability of HEDO to inhibit cell growth in Ontario Cancer Institute (OCI)-LY3 lymphoma cells by preventing nuclear factor-kappa B (NF-κB) signaling. In addition, HEDO induced apoptosis by instigating the activation of Bcl-2-associated X (BAX) and cleaved caspase-3, decreasing B-cell lymphoma 2 (BCL2), B-cell lymphoma-extra large (BCL-XL), and procaspase 3 expression levels. Based on these findings, we suggest that HEDO has potential as an anticancer drug of lymphoma by inducing ROS-dependent accumulation of SubG0/G1 arrest and apoptosis in OCI-LY3 cells.