Katharina was the daughter of Mladen II Šubić, Ban of Croatia and Lord of all of Bosnia.
[1] Katharina married Bolesław III the Generous, Duke of Legnica-Brzeg, in 1326, four years after the death of his first wife, Princess Margareta of Bohemia.
After the abdication of her husband in 1342, Katharina retired with him to Brzeg, where they remained until Bolesław III's death ten years later, on 21 April 1352.
This was the second documented case where a Piast ruler granted his widow lands in her own right; the first was Salome of Berg, who received Łęczyca from her husband Bolesław III Wrymouth when he died in 1138.
The terms of the dower grant stated that the beneficiary could obtain the full sovereignty over the land for her life, and could lose it in two cases: if she remarried or became a nun (resignation was not considered).