Lefebvre made her professional debut on 24 January 2015, scoring a four-round points decision (PTS) victory against Bojana Libiszewska at the Salle Marie-José Pérec in Fourmies, France.
[4] After compiling a record of 3–0 (0 KOs), she defeated Taoussy L'Hadji via majority decision (MD) to capture the French female super-featherweight title on 22 April 2016 at the Salle Gayant in Douai, France.
[5] Two fights later she defeated Gabriella Mezei via unanimous decision (UD) on 4 November 2016 in Douai, capturing the vacant WBF International female super-bantamweight title.
[6] In her next fight she challenged for her first world championship, facing Simone Da Silva Duarte for the vacant WBF female super-bantamweight title on 10 March 2017 at the Salle Gayant.
[11][12] On 13 April 2024, Lefebvre lost her WBO championship to England's Ellie Scotney suffering the first defeat of her professional career by unanimous decision in a fight that was also for her opponent's IBF title and the vacant Ring Magazine belt.