Catherine was the fourth of the eight children of Bridget of Sweden and Ulf Gudmarsson. Married young to a noble named Eggard van Kürnen, the couple — under the influence of Bridget — took mutual vows of chastity. In 1349 Eggard fell ill; Catherine, twenty-eight, travelled to Rome to be with her mother, who was already settled there as a permanent religious widow.
Eggard died during Catherine's absence; she did not return to Sweden but stayed with her mother for twenty-four years, sharing in her diplomatic mission to Rome and the papal court, her embassies to Avignon, and her pilgrimage to the Holy Land (1372). After Bridget's death in 1373, Catherine carried her mother's body home to Sweden in 1374, and presided over the foundation of the great mother-abbey of the new Order of the Most Holy Saviour at Vadstena, becoming its first abbess.
Most of the rest of her life was spent in shuttle-diplomacy between Vadstena and Rome — negotiating with the Roman pope Urban VI for the canonization of her mother, gathering signatures from European royalty and bishops for the canonization dossier, and writing the Sjelinna Thrøst ('Consolation of the Soul'), a Swedish devotional work. Bridget was canonized in 1391 — Catherine did not live to see it; she died at Vadstena on March 24, 1381. The cult of mother and daughter together has been venerated at Vadstena for six and a half centuries.