Chemical investigation of the ethanolic extracts of the dried leaves of Bergenia purpurascens led to the isolation and identification of a new aromatic glycoside, 1-O-β-D-glucopyranosyl-2-methoxy-3-hydroxyl-phenylethene (1), along with other 19 known compounds (2-20). The structure of compound 1 was determined by a detailed analysis using various analytical techniques, including 1D and 2D NMR. In vitro anti-proliferative activities of compound 1 on five human cancer cell lines were evaluated. The results showed that compound 1 possessed the most potent effects with the IC50 values of 14.36 ± 1.04 μM against T24 cells. The further bioactivity analysis showed that compound 1 induced apoptosis of T24 cells, and altered anti- and pro-apoptotic proteins, leading to mitochondrial dysfunction and activation of caspase-3 for causing cell apoptosis. The present investigation illustrated compound 1 might be used as a potential antitumour chemotherapy candidate.