Gabrielle Debillemont-Chardon was born to a family of musicians, who encouraged her interest in the arts. Her father, Jean-Jacques-Joseph Debillemont, was a composer and conductor, and her sister Jeanne Debillemont was a pianist. But rather than music, G. Debillemont-Chardon chose to study drawing and miniature painting with miniaturists Pierre Paul de Pommayrac (1807-1880) and Antonin Pierre Topart (1833-unknown), and with painter Émile Lévy (1826-1890). She started exhibiting at the Salon des Artistes Français in 1877 and won several prizes.
In addition to her artistic career, she devoted herself to women’s education. Between 1881 and 1896 she worked as a drawing teacher at several Paris municipal schools, and from 1884 to 1892 as the director of a drawing school funded by the administration of the 10th arrondissement. In 1885 she started giving private miniature lessons at home, tutoring women of various nationalities, such as Marie Laforge (1865-1942) from France, Berta Wilhelmson (1869-1965) from Sweden, Sara Page (1855-1943) from Britain and Sonia Routchine-Vitry (1878-1931) from Russia. These lessons not only provided her with extra income, but also enabled her to defend and promote the art of miniature painting.

The genre had experienced somewhat of a decline since the 19th century due to the advent of photography. G. Debillemont-Chardon belonged to a number of artistic groups that worked towards the rehabilitation of the practice. She became vice-president then president of the Société de la Miniature, de l’Aquarelle et des Arts Précieux (Miniature, watercolour and precious arts society) and a member of the Société des Miniaturistes et Enlumineurs de France (French society of miniaturists and illuminators). She was also invested in the promotion of women’s art and became the vice-president of the Union des Femmes Peintres et Sculpteurs (UFPS, Union of women painters and sculptors) in 1901, eventually becoming its chair in 1934. She also served as group president in charge of exhibitions and sales at the Arts de la Femme de l’Étoile event in 1912.

G. Debillemont-Chardon gained international recognition as a reformer of miniature painting. British journal The Studio described her in glowing terms in 1910. She used this acknowledgement to affirm and promote her views about the art. In 1909 she published La Miniature sur ivoire. Essai historique et traité pratique, prefaced by Léonce Bénédite, the director of the Musée du Luxembourg. In the book, she strove to demonstrate how serious and valuable miniature art was – in her eyes as important as oil painting – and advocated for the genre to modernise its techniques in accordance with the times: broad brushstrokes for the background, contrast between the clothing and the precision of the faces in portraits, and working outdoors. Her career reached its height in 1928 when she was made Knight of the Legion of Honour for her work as a miniaturist.
Thanks to her success, her works were included in several public collections. Her Femme au grand chapeau [Woman in a large hat, 1901, Jeune nymphe [Young nymph, date unknown], Portrait de fillette au bonnet brodé [Portrait of a young girl in an embroidered bonnet, 1901] and Portrait d’une femme en deuil [Portrait of a woman in mourning, 1902] are held by the Musée d’Orsay. Others are kept at the Petit Palais in Paris (Jeune fille assise [Young girl sitting, 1919] and Jeune fille [Young girl, 1903]) and at the Musée Lambinet in Versailles (Victor Hugo et Marion de Lorme). Her work is now mostly forgotten.