The Duchess founded the monastery after husband's death in 1280 and also entered it herself. She relinquished her Sącz estates, namely Stary Sącz with 28 villages, to the monastery. She died in 1292, and her tomb is located in the monastery. The monastery church of St Clare, which was consecrated in 1332, was originally mainly wooden. It was rebuilt several times over the centuries. However, the most influential part of the monastery's current appearance was the early 17th-century reconstruction by the Italian mason Jan de Simoni. After his changes, the monastery acquired a typically Baroque appearance.

Particularly noteworthy in the church are the main altar, which houses the painting of the Holy Trinity, and the stucco scene of the Assumption of the Blessed Virgin Mary. Also beautiful are the 17th-century paintings of St Anthony and St Clare in the side altars and the unique Baroque pulpit, which was erected in 1671, as well as the 15th-century baptismal font in the vestibule. Adjoining the monastery is the 14th-century Chapel of Saint Kinga, which houses a Baroque altar with a statue depicting the Holy Duchess of Sącz from 1470. Unique is also the 17th-century door leading into the sacristy, which features painted scenes from the lives of Saint Kinga and her husband, Bolesław the Chaste. Stary Sącz soon became a place of worship for Saint Kinga. Her figure is mainly associated with Stary Sącz through her presence in religious worship and living historical tradition as well as legends, art and literature. In 1999, Pope John Paul II canonised Saint Kinga. The celebrations took place in the Stary Sącz marshes. The altar erected then can still be seen today. Also present at the canonisation Mass were the Poor Clare nuns from Stary Sącz, who had obtained permission to go outside the monastery cloister, especially for the occasion.