Background: Searching for new cytotoxic agents with apoptosis induction may represent a viable strategy for cancer treatment to overcome the increased resistance to available anticancer agents. Objective: The purpose of the current study was aimed at preparation and anticancer evaluation of two new series of 2H-quinolinone and halogenated 2H-quinolinone derivatives against two cancer cell lines. Methods: Two new series of 2H-quinolinone and halogenated 2H-quinolinone derivatives were prepared and screened for their cytotoxicity against breast MCF-7 and liver HepG-2 cancer cell lines as well as normal breast MCF-10a. Results: The tested molecules revealed good cytotoxicity and selectivity toward cancer cell lines relative to normal cells. These compounds were analyzed by DNA flow cytometry on MCF-7 cells. They were found to cause G2/M phase arrest and induced apoptosis at the pre-G1 phase. In addition, increased caspase 3/7 activity and decreased osteopontin expression verified the apoptotic activity. Conclusion: The potent compounds discovered in this study can be a hit for the discovery of new cytotoxic agents and are worthy of further investigation.