The WCRP Workshop on Extremes in Climate Prediction Ensembles (ExCPEns) was held online from October 25 to 27, 2021, and co-hosted by the World Climate Research Programme (WCRP), Pusan National University, and the APEC Climate Center. The workshop focused on employing subseasonal, seasonal, annual to decadal, and longer-term prediction ensembles to improve the prediction and understanding of extreme weather and climate events. The 3-day workshop consisted of six sessions including 42 oral presentations and 26 poster talks. The workshop was announced through various target groups and communities to promote better participation by related stakeholders, such as the WMO (World Meteorological Organization) S2S group, Young Earth System Scientists (YESS) community, WMO Southeast Asia, APCC networks, APN networks, and WCRP networks.