Jerôme Mesnager joined the École Boulle, a school of fine arts and crafts and applied arts, in 1974, where he followed the cabinetmaking course, and where he stayed as a teacher.
In 1982, he co-founded Zig-Zag, a group of very young artists who decided to take over the streets by drawing graffiti and to occupy abandoned factories through artistic performances.
On the 16th of January 1983, he invented 'The man in white', "a symbol of light, strength and peace". Jerôme Mesnager drew this white silhouette in the entire world: from the walls of Paris to the Chinese Wall. For the artist, it is reminder for the human kind that our evil malady is not incurable and that we can go back to our true self: a high minded species, capable of empathy and happiness.
In 1995, he produced a large mural painting in the Ménilmontant street in Paris, "C'est nous les gars de Ménilmontant"; this artwork is an homage to Matisse’s 'La Danse'.
Jerôme Mesnager is often associated with Nemo, a character with a black silhouette wearing a raincoat and a hat. He was part of the Paris street art scene, with artists such as Blek le rat, Miss Tic, Jef Aérosol, Némo, etc. and of the Free Figuration movement in the early 80s.
In 2006, he produced a series of paintings inspired by art nouveau and art deco. The same year, hedrew his white characters in the Hôtel des Academies et des Arts in Paris.