She was the eighth child and sixth daughter of King Louis XV of France and his charitable wife, Marie Leszczyńska who was nicknamed "The Good Queen" by the common people.

[5] According to Madame Campan’s memoirs, while their education had been neglected in the convent, they compensated for this and studied extensively, after their return to court, encouraged by their brother, Louis, with whom they immediately formed a close attachment.

Charles Philippe d'Albert, 4th Duke of Luynes noted that Sophie and her siblings would assist their mother Marie Leszczyńska on various charitable activities she initiated outside Versailles such as giving money and clothes to the poor on various parishes.

From April 1774, Madame Sophie, along with her sisters Adélaïde, Victoire and Louise, attended their father, Louis XV, on his deathbed until his death from smallpox on 10 May.

Despite the fact that the sisters had never had smallpox, the Mesdames were allowed to attend him, even while other male members of the royal family, as well as the Dauphine, Marie Antoinette, were kept away due to the serious risk of catching the illness.

The sisters did catch smallpox from their father's deathbed, and were kept in quarantine in a little house near the Château de Choisy, to which the court evacuated after the death of the King, until they eventually recovered.

[16] However, they distanced themselves from court and often preferred to reside in their own Château de Bellevue in Meudon; they also traveled annually to Vichy, always with a retinue of at least three hundred people, and made the waters there fashionable.

[17] The Mesdames continued to be the confidants of Louis XVI, and they also maintained a good relationship with their niece, Princess Élisabeth of France, and often visited her in her retreat at the Domain of Montreuil.

[17] The Austrian Ambassador, Florimond Claude, Comte de Mercy-Argenteau, reported that their salon was a center of intrigues against Marie Antoinette, where the Mesdames tolerated poems satirizing the queen.

[citation needed] Her great-niece, Sophie Beatrix, youngest daughter of Louis XVI and Marie Antoinette, was named after her.