Tetraploidy is a hallmark of cancer cells, and tetraploidy‐selective cell growth suppression is a potential strategy for targeted cancer therapy. However, how tetraploid cells differ from normal diploids in their sensitivity to anti‐proliferative treatments remains largely unknown. In this study, we found that tetraploid cells are significantly more susceptible to inhibitors of a mitotic kinesin (CENP‐E) than are diploids. Treatment with a CENP‐E inhibitor preferentially diminished the tetraploid cell population in a diploid–tetraploid co‐culture at optimum conditions. Live imaging revealed that a tetraploidy‐linked increase in unsolvable chromosome misalignment caused substantially longer mitotic delay in tetraploids than in diploids upon moderate CENP‐E inhibition. This time gap of mitotic arrest resulted in cohesion fatigue and subsequent cell death, specifically in tetraploids, leading to tetraploidy‐selective cell growth suppression. In contrast, the microtubule‐stabilizing compound paclitaxel caused tetraploidy‐selective suppression through the aggravation of spindle multipolarization. We also found that treatment with a CENP‐E inhibitor had superior generality to paclitaxel in its tetraploidy selectivity across a broader spectrum of cell lines. Our results highlight the unique properties of CENP‐E inhibitors in tetraploidy‐selective suppression and their potential use in the development of tetraploidy‐targeting interventions in cancer.