Prim-O-glucosylcimifugin is a major constituent in Radix Saposhnikovia that has been long used for the treatment of pyrexia, rheumatism, and cancer in traditional Chinese medicine. However, the molecular and cellular mechanisms remain unknown regarding the therapeutic effect of prim-O-lucosylcimifugin. Here, we investigated the effects of prim-O-glucosylcimifugin on cell cycle progression and apoptosis in human acute lymphoblastic leukemia cells. Prim-O-glucosylcimifugin treatment resulted in marked increases in cell apoptosis and cell cycle arrest at the G2/M phase. Mechanistically, prim-O-glucosylcimifugin induced the degradation of β-tubulin and downregulated phosphorylated CDK1 levels, a molecular indicator in the G2/M cell cycle arrest. Furthermore, activation of caspase-3, caspase-8, and caspase-9 was involved in the prim-O-glucosylcimifugin-induced apoptosis. Our study reveals the anticancer activity of prim-O-glucosylcimifugin and the potential underlying mechanisms.