ÎČâCatenin is a multifunctional protein and participates in numerous processes required for embryonic development, cell proliferation, and homeostasis through various molecular interactions and signaling pathways. To date, however, there is no direct evidence that ÎČâcatenin contributes to cytokinesis. Here, we identify a novel pâS60 epitope on ÎČâcatenin generated by Plk1 kinase activity, which can be found at the actomyosin contractile ring of early telophase cells and at the midbody of late telophase cells. Depletion of ÎČâcatenin leads to cytokinesisâdefective phenotypes, which eventually result in apoptotic cell death. In addition, phosphorylation of ÎČâcatenin Ser60 by Plk1 is essential for the recruitment of Ect2 to the midbody, activation of RhoA, and interaction between ÎČâcatenin, Plk1, and Ect2. Timeâlapse image analysis confirmed the importance of ÎČâcatenin phosphoâSer60 in furrow ingression and the completion of cytokinesis. Taken together, we propose that phosphorylation of ÎČâcatenin Ser60 by Plk1 in cooperation with Ect2 is essential for the completion of cytokinesis. These findings may provide fundamental knowledge for the research of cytokinesis failureâderived human diseases.