CKS ensures proper meiotic chromosome segregation. During meiosis I, the CDK1–CKS complex works with cyclins B1 and B3 to promote activation of the APC/C, which in turn degrades securin to ensure the metaphase-to-anaphase transition. During meiosis II, the cyclin B3–CDK1–CKS complex promotes the metaphase-to-anaphase transition by positively regulating the ZYG-11/CUL-2 ubiquitin ligase to target cyclin B1 for degradation. During both meiotic divisions, the cyclin B1/3–CDK1–CKS complex promotes anaphase B chromosome segregation via an unknown mechanism that likely involves meiotic spindle remodeling factors. The CDK1–CKS cartoon is based on an AlphaFold3 model of the predicted C. elegans complex.