Introduction and Aim: Cyperus rotundus (L.), commonly known as nutgrass, has been in use in Indian medicine traditional system against several ailments. This investigation was performed to assess the in vitro antineoplastic activity of extracts prepared from water and ethanol with C. rotundus rhizomes. Materials and Methods: Toxic effects induced by the C. rotundus extracts on MCF-7 breast adenocarcinoma cells was evaluated using Sulphorhodamine- B (SRB) Assay, Trypan blue assay, Hoechst nuclear staining assay, Acridine Orange-Ethidium bromide (AO-EB) differential fluorescence staining assay and DNA fragmentation assays. Results: The results of SRB assay indicated the IC50 value of aqueous extract as 510.887 µg/mL and that of ethanol extract as 122.98 µg/mL. Trypan blue assay also indicated the similar results, wherein ethanol extract exerted higher cytotoxicity compared to the aqueous extract. MCF-7 cells treated with aqueous and ethanol extracts of C. rotundus rhizomes were exposed to Hoechst staining and AO-EB nuclear staining assays, wherein and ethanol extract induced clear apoptotic bodies in the tested cells. Further, the cells were treated with the ethanol extract and DNA fragmentation was confirmed by DNA ladder assay. MCF-7 cells administered with ethanol extract were subjected to DNA fragmentation assay for assessing the apoptosis induction nature of the extract. Conclusion: Results from our study indicate a promising approach into the possibility of developing C. rotundus ethanol extract into an effective anticancer moiety after appropriate pre-clinical and clinical validations.