Madame Thénardier, born in 1788, co-manages an inn in Montfermeil with her husband. She presents a physically imposing figure with black hair and green eyes, differing from the novel's portrayal of her as blond. Her personality is defined by greed, cruelty, and pragmatism; she routinely employs manipulation and threats for financial gain. She possesses a volatile temper, frequently erupting in yelling and swearing. She shows no affection toward her husband and openly disrespects him, despite their criminal partnership.

She and her husband exploit Cosette, whom they care for under false pretenses. They force the child into hard labor, deny her sufficient food and clothing, and subject her to physical abuse. Simultaneously, they invent expenses to extort money from Cosette's mother, Fantine. Madame Thénardier displays clear favoritism toward her daughters Éponine and Azelma, permitting them to mistreat Cosette and spoiling them with resources paid for by Fantine. Her relationship with her son Gavroche is distant and neglectful.

After Jean Valjean rescues Cosette in 1823, the Thénardiers lose their inn through bankruptcy. They relocate to Paris, adopting the alias "Jondrette" and living in poverty at Gorbeau House. There, Madame Thénardier joins her husband's schemes, writing fraudulent letters to philanthropists and collaborating with the Patron-Minette criminal gang to survive. In February 1832, she assists in luring Valjean to their apartment under false pretenses to rob him. The ambush fails, resulting in her arrest alongside her husband and Patron-Minette members.

Unlike the novel where she dies in prison, the anime shows her incarceration followed by release in early 1833. She then returns to Montfermeil with her younger daughter Azelma, intending to reopen the inn independently and rebuild her life without her imprisoned husband. This outcome marks a shift toward self-reliance, though her motivations remain rooted in financial independence rather than moral redemption.