A library of imidazopyrimidine-propenone conjugates (8a-8g) were synthesized and evaluated for their antitumor activity against three human cancer cell lines namely prostate (DU-145), lung (A549) and breast (MCF-7) cancer. These conjugates showed good to moderate activity against the tested cell lines. Among them two conjugates (8c and 8d) showed significant antiproliferative activity against human lung cancer cell line (A549) with an IC50 values of 1.236 μM and 1.327 μM respectively. Flow cytometric analysis revealed that these conjugates 8c and 8d arrest the cell cycle at the G2/M phase and induce cell death by apoptosis. The tubulin polymerization assay showed that these compounds 8c and 8d effectively inhibited the microtubule assembly in human lung cancer cells (A549). The molecular modeling studies showed that the compound 8c interacts and binds efficiently with the tubulin protein at the colchicine site. Overall, the present investigation demonstrated that the synthesized imidazopyrmidine-propenone conjugates are promising tubulin inhibitors.