After the early death of her father in 1326, Agnes and her older sister Katharina (later by marriage Lady of Coucy) were placed under the guardianship of their paternal uncles, Frederick the Fair and Albert II.
On 1 June 1338 Agnes married with Bolko II the Small, Duke of Świdnica, who wanted with this union to enhance his international position against the House of Luxembourg, direct competitors of the Habsburgs.
The marriage apparently was childless, although some sources stated that they had two children: a daughter, Elisabeth (d. 1407) and a son, Bolko, who, according to old Silesian legend, died with only nine-years-old, accidentally killed by the court jester Jakob Thau, when he threw a stone to him during a game.
Agnes died on 2 February 1392 in Świdnica and was buried in the Franciscan Princely Chapel (Fürstenkapelle) of the Grüssau Abbey. According to the treaty of 1353 between Bolko II and the Emperor Charles IV, on her death the duchies were incorporated into the lands of Bohemia by Wenceslaus, King of the Romans.
Under the rule of the Abbot Benedict II Seidel (1735–1747) was built in the Fürstenkapelle a sculpture of white marble from Agnes, which is still there.