[3] Born as princess of the Znojmo Appanage (named after its centre, the town of Znojmo in southern Moravia), she later became by marriage Duchess of Sandomierz (1173-1194), Grand Duchess of Kraków and the Seniorate Province (1177-1194), Duchess of Masovia (1186–1194), and Duchess-regent of Kraków and the Seniorate Province, Sandomierz, and Masovia on behalf of her minor sons from 1194–1198, then the latter two duchies plus Kuyavia until 1199/1200.

Helen married Casimir II the Just, youngest son of Bolesław III Wrymouth, probably shortly after his return from captivity,[4] which at the latest was before 1161.

In 1198, they reached an agreement: Mieszko would take Kraków, in return for which he gave Helen and her sons Kuyavia (they retained Masovia and Sandomierz).

Independent authority over the inheritance was assumed by the eldest son, Leszek the White, in 1199 or 1200.

Helen's intelligence and character were recorded in the chronicle of Vincent Kadlubek, who knew the princess in person.