Most of what is known about her comes from the biography written two years after her death by one of her fellow nuns, Suor Jacopa Pollicino, daughter of the Baron of Tortorici.

While her mother was pregnant with her, Messina was stricken with the plague, and her parents fled the city for the small town of Santissima Annunziata, near Messina, where the child was born on 25 March 1434, the feast of the Annunciation, and in that year also Holy Thursday.

[3] Eustochia was a great lover of the poverty that marked the Poor Clares and felt that Basicò did not adhere strictly enough to the rule in this regard.

After discussions with the sisters and the abbess, and with the approval of Pope Callixtus III, in 1464 she decided to found a new convent which became known as Montevergine ("Mountain of the Virgin").

Eustochia was chosen abbess, and at the time of her death the convent was home to 50 sisters.