Chrysosplenol D, a flavonol isolated from Artemisia annua L., can exert anticancer effects. This study investigated the anticancer property of chrysosplenol D and its underlying mechanism in oral squamous cell carcinoma (OSCC). We observed that chrysosplenol D reduced cell viability and caused cell cycle arrest in the G₂/M phase. The findings of annexin V/propidium iodide staining, chromatin condensation, and apoptotic-related protein expression revealed that chrysosplenol D regulated apoptosis in OSCC. Furthermore, chrysosplenol D altered the expression of the autophagy marker LC3 and other autophagy-related proteins. Phosphatidylinositol 3-kinase/protein kinase B, extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase (MAPK) were downregulated by chrysosplenol D, and the inhibition of these pathways significantly enhanced chrysosplenol D-induced cleaved poly (ADP-ribose) polymerase activation. Moreover, the upregulation of heme oxygenase-1 (HO-1) was found to be critical for chrysosplenol D-induced apoptotic cell death. The analysis of clinical data from The Cancer Genome Atlas and Gene Expression Omnibus datasets revealed that patients with head and neck cancer had lower HO-1 expression than did those with no head and neck cancer. The findings of the present study indicated that chrysosplenol D exerts anticancer effects on OSCC by suppressing the MAPK pathway and activating HO-1 expression.