[1] She was elected under the auspices of the Belgian Workers Party to represent the district of Liège in 1929 at age 54 and served until 1936.
Dejardin was born into a family of miners (her mother, Marie-Rosette, gave birth to one of her ten siblings in a mine) in Grivegnée and dropped out of school at 10 years old to become work in mines and attending her first political demonstration with her brothers at age 11.
[5][6] Dejardins founded the Belgian Women's International League for Peace and Freedom, was a co-founder of the Women's Socialist League, and of the feminist newspaper La Voix de la Femme.
Dejardin was able to cast a vote due to her special status as a former political prisoner.
After the end of World War II, she returned to Belgium and ran for office again, replacing the deceased Georges Truffaut in the Chamber in 1944.