Dutch Roman Catholic theologian, successor to Gerhard Groote as leader of the Brethren of the Common Life, a community of laymen dedicated to the care and education of the poor, and founder of the monastic Congregation of Windesheim.

Educated at the University of Prague, Radewyns returned to Leerdam and became Groote's friend and disciple (c. 1380) in the devotio moderna movement. He was ordained priest and became vicar of Deventer, where he and Groote formed the Brethren of the Common Life. In 1387 Radewyns founded the monastery of Windesheim, at the village of the same name, near Zwolle, Neth. It became a congregation of Augustinian Canons. Thomas à Kempis, a student who lived for a time with the Brethren, wrote a biography of Radewyns.