A novel series of 2-arylquinazolinones 7a-o bearing trans-stilbene moiety were designed, synthesized, and evaluated against human breast cancer cell lines including human breast adenocarcinoma (MCF-7 and MDA-MB-231) and human ductal breast epithelial tumor (T-47D). Among the tested compounds, the sec-butyl derivative 7h showed the best profile of activity (IC₅₀ < 5 μM) against all cell lines, being 2-fold more potent than standard drug, etoposide. Our investigation revealed that the cytotoxic activity was significantly affected by N3-alkyl substituents. Furthermore, the morphological analysis by acridine orange/ethidium bromide double staining test and flow cytometry analysis indicated that the prototype compound 7h can induce apoptosis in MCF-7 and MDA-MB-231 cells.