Contessina Antonia Romola di Lorenzo de' Medici (6 January 1478 – 29 June 1515) was an Italian noblewoman, ninthborn and fifth and last daughter of Lorenzo the Magnificent, Lord of Florence, and his wife Clarice Orsini.

She was the wife of the Florentine Piero Ridolfi, later made Count Palatine by her elder brother Pope Leo X.

Contessina de' Medici was born on 16 January 1478 in Pistoia, where her mother and her siblings had taken refuge after the Pazzi conspiracy.

In May 1494 she married the Piero Ridolfi (1467–1525): a careful marriage to a man from a local Florentine family, planned by her father Lorenzo to counter local anxieties about the ambitions of the Medici, since Florentines were alarmed by the marriages of her siblings Piero and Maddalena to powerful families from other cities.

In 1513 her brother Giovanni was elected Pope with the name of Leo X. Contessina then moved to Rome with her sisters Lucrezia and Maddalena, where she established herself as an influential woman in papal politics.