Justine Percoli-Suárez was born on 27 November 1811 in Florence as the daughter of Bernard Percoli and Julie Niccolini. Her first marriage was to Marquess Luigi Bartolini-Baldelli, but she was widowed at an unknown date, leaving her a wealthy widow.
In 1840, she married Jérôme Bonaparte, former King of Westphalia, in a religious ceremony. He had previously been married to Elizabeth Patterson and Catharina of Württemberg. A second (secret) civil ceremony took place on 19 February 1853. Her money helped to alleviate some of his financial troubles, but the marriage was considered to be morganatic, and he continued to call her Madame la Marquise. She agreed to this at first, but she would later insist on being recognised.
She moved to France with him in 1847 where they joined his son from his second marriage, Napoléon-Jérôme. Her stepson took an intense dislike to her and tried to alienate her from his father. Jérôme eventually took a mistress and sent Justine back to Florence.
Justine was widowed in 1860, and she was awarded a pension by Napoleon III. She outlived her husband for many years, dying on 30 January 1903.