Léon was born to chocolate makers Pierre-Paul Léon and Mathrine Telohan in Paris on 28 September 1768. Léon was one of six children. Her father died in 1784, after which time Léon helped her mother with the chocolate business in exchange for room and board. She was also responsible for helping to raise and support her siblings. It is believed that she became a political radical after witnessing the execution of leaders of a bread riot.
On 6 March 1792 she addressed the Legislative Assembly on behalf of Parisian women, suggesting that a female militia be formed so that women could protect their homes from counter-revolutionary assaults. In July 1791 she signed the petition at the Champ de Mars. Léon was a founder of the Society of Revolutionary Republican Women (Société des Républicaines-Révolutionnaires) along with Claire Lacombe and became its president on 9 July 1793. Léon and Lacombe both held strong hatred towards Lafayette, mostly due to his wartime opinions and actions. The Société only lasted for about a year before authorities shut it down. She was also a leader of the Femmes Sans-Culottes in 1793. She also was a frequenter of the Cordeliers Club. At age 29, she married Théophile Leclerc, the leader of the Enragés. They were later arrested together, but held separately in the Luxembourg prison from April to August, 1794.
Little is known about Léon's later life. She died at home in Bourbon-Vendée on 5 October 1838.
- Fairweather, Maria (27 Sep 2006). "Femininity as well as fraternity in France 1789". telegraph.co.uk. Retrieved 2009-06-01.
- Godineau, Dominique; Streip, Katherine (1998). The women of Paris and their French Revolution. University of California Press. ISBN 0-520-06719-3. Retrieved 2009-06-01.
- Darline Gay Levy, Harriet Branson Applewhite, Mary Durham Johnson. Women In Revolutionary Paris, 1789-1795. University of Illinois Press. 1981.