Chomat was born at Saint-Etienne (Loire), her father having died a few months earlier, while on active service in the First World War.
[2] She committed herself to the French Communist Party in 1934 and helped found the Union of Young Girls in France (l'Union des Jeunes Filles de France) in 1936, with Danielle Casanova, Marie-Claude Vaillant-Couturier, and Jeannette Vermeersch.
In 1937, she married Victor Michaut [Wikidata], a communist leader; the marriage lasted ten years.
At the end of 1939, she participated in the reorganization of the French Communist Party (PCF) which had been made illegal by the Edouard Daladier government.
As Casanova's wife, she suffered the disgrace of the party following the Servin-Casanova scandal in 1961.