A series of novel N‐aryl‐5‐(benzo[d][1,3]dioxol‐5‐ylmethyl)‐4‐(tert‐butyl)thiazol‐2‐amines (C1‐C31) were synthesized and evaluated for their antitumor activities against HeLa, A549 and MCF‐7 cell lines. Some tested compounds showed potent growth inhibition properties with IC50 values generally below 5 μM against the three human cancer cells lines. Compound C27 showed potent activities againt HeLa and A549 cell lines with IC50 of 2.07 ± 0.88 μM and 3.52 ± 0.49 μM respectively. Compound C7 (IC50 = 2.06 ± 0.09 μM) was the most active compound against A549 cell lines, while compound C16 (IC50 = 2.55 ± 0.34 μM) showed the best inhibitory activity against MCF‐7 cell line. The preliminary mechanism of the inhibitory effect was investigated via further experiments, such as morphological analysis by dual AO/EB staining and Hoechst 33342 staining, cell apoptosis and cycle assessment by FACS analysis. The results illustrated that the antitumor activity of compound C27 might be associated with its induced S‐phase and G2/M‐phase arrests and apoptosis in HeLa cell line, and could be developed as a potential antitumor agent.