Abstract Objectives Cancer chemotherapeutic treatments come with many adverse effects. Anticancer studies with natural products have been carried out to minimize these issues. This study aimed to evaluate the anticancer potential of endemic Phlomis brevibracteata Turrill against four different hepatocellular carcinoma (HCC) cell lines and find new natural candidates for cancer treatment. Methods The chemical composition of 70 % aqueous methanol extract (PBM) of P. brevibracteata was analyzed using the LC-MS/MS method. Additionally, the effect of PBM on the proliferation, motility, and oxidative state of four different HCC cell lines of SK-HEP-1, PLC/PRF/5, HuH-7, and Mahlavu have been investigated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), wound healing, and DCFH-DA assays respectively. Results Our results identified caffeoylquinic acids and Forsythoside B as the main chemical constituents of the PBM. A significant decrease in cell viability was recorded at certain extract concentrations. The motility of the HCC cell lines was inhibited at different levels when treated with PBM. PBM reduced basal and induced oxidative states in a concentration-dependent manner. Conclusions We conclude P. brevibracteata plant extract can be a potential candidate for further studies with the goal of new anticancer chemotherapeutic discovery.