At an early age, Annetta and Paola lost their parents when they were killed at sea. As orphans, and left with little choice of livelihood, Paola chose a life in prostitution, while Annetta became the live-in maid of the Auditore family in Florence, who were secretly a family of Assassins.
In 1476, Giovanni, Federico, and Petruccio Auditore were arrested in their home on false crimes of treason. Annetta, Maria Auditore da Firenze and Claudia Auditore da Firenze hid in the home after the arrests. After Annetta almost hit Ezio Auditore da Firenze with a frying pan, he suggested that she take his mother and sister to a safe place, to which she suggested her sister's place. After meeting Ezio there, Annetta was amused by his reaction, once he saw that her sister ran a brothel.
Annetta later came to live with the Auditore family again, this time at the Villa Auditore in Monteriggioni, where Ezio had escorted his family. Some time after, Annetta chose to move back to Florence to stay with her sister, until her death in around 1511.
- In Assassin's Creed: Renaissance, it's mentioned that Annetta was Ezio's wet-nurse, even though she was only 2 years older than him.
- Annetta's parents supposedly died at sea in 1446 or 1447, but Annetta was born in 1457.
- Annetta is a diminutive of the name Anna, itself derived from Hebrew Channah, חַנָּה, meaning "favor" or "grace".