Larmignat was born as Eugénie-Marguerite Mesnard in Châteauroux, Centre-Val de Loire, France, on 9 February 1911. She was the youngest of eleven children. While her real first name is Eugénie-Marguerite, she preferred using Marguerite, having always disliked Eugénie. Her earliest memory was from the age of 3, when the police announced her brother’s death to her parents.
During her life, she worked as a secretary (both as an executive secretary at an insurance company in Chartres and even at the military base in Déols). Her husband died in the 1960s.
In 1997, she moved to Nébouzat and never again left the department of Puy-de-Dôme. She moved to retirement home in October 2017.
Larmignat passed away in Saint-Ours, Puy-de-Dôme, Auvergne-Rhône-Alpes, France, on 11 July 2023, at the age of 112 years, 152 days.