Born September 28, 1982, in the Breton city of St. Renan, Leroy was the daughter of professional footballer Jean Luc le Magueresse. Raised in a series of different locales per her father's team transfers, she later attended college at Saint-Yorre's Collège des Célestins, where a music teacher encouraged her to study violin. Leroy also exhibited a talent for graphic arts, and at age 13 won a national drawing contest that awarded her the opportunity to distribute art supplies in Mali. After a brief return to France, she entered a foreign exchange program and spent a year studying in the U.S., including a two-day course at Cincinnati's Performing Arts School. The experience was pivotal in convincing Leroy to pursue a career as a singer, and upon arriving home she enrolled in classical vocal classes at the Clermont-Ferrand Conservatoire, concurrently studying law with an eye on a fallback calling in international diplomacy. A fan of the fledgling TV series Star Academy, Leroy signed up to study under program judge and music teacher Armande Altaï in 2001, who encouraged her new pupil to audition for the show's sophomore season. The night she was selected as a finalist, Leroy also received word she was chosen to star as Scarlett O'Hara in Autant en Emporte le Vent, a French stage musical adaptation of the classic novel Gone with the Wind. Leroy ultimately opted for Star Academy and her faith was rewarded on December 21, 2002, when she was crowned champion in viewer voting.

Leroy's self-titled debut LP followed in March 2003, launching the hit singles "Cassé" and "Suivre une Étoile." For her 2005 follow-up, Histoires Naturelles, Leroy teamed with legendary French pop composer Laurent Voulzy, forging a mystical, deeply romantic record that earned critical comparison to the likes of Kate Bush and Tori Amos. In 2007, Leroy began work on her third album, with Teitur Lassen in the production chair. Released in 2009, Le Cheshire Cat & Moi became the first album that featured all the lyrics written by Leroy herself.

At the end of 2010, Leroy released her fourth album, Bretonne, the biggest hit of her career. The album featured songs sung in four languages (Gaelic, French, English, Breton) and included covers of traditional Celtic songs as well as more contemporary numbers. It saw Leroy return to the top of the French charts for the first time since her 2003 self-titled debut, and stay there for six weeks. In 2012, Bretonne was repackaged with a revised track list for the U.S. market under the title Nolwenn. Her proper follow-up, Ô Filles de l'Eau, appeared later that year; thanks to the moderate hit single "Juste Pour Me Souvenir," it reached number five in France. An accompanying concert album, Ô Tour de l'Eau, was released in 2014. ~ Jason Ankeny