A new series of imidazo[2,1-b]pyridine/pyrimidine chalcone derivatives were synthesized and evaluated for their anticancer activity. These chalcone derivatives showed promising activity with GI50 values ranging from 0.28 to 30.0 mM. The detailed biological aspects of one of the promising compound 3f on the MCF-7 cell line were studied. Interestingly, compound 3f induced G1 cell cycle arrest, down regulation of G1 phase cell cycle regulatory proteins such as cyclin D1, E1, and CDK2. Moreover, compound 3f showed the characteristic features of apoptosis such as enhancement in the levels of p27 and TNFR1 proteins with concomitant down regulation of procaspase-9. One of the representative compound of this series 3f could be considered as the potential lead for its development as a new anticancer agent.