She was a member of the noble House of Baux of the Kingdom of Naples, which had its origins in Provence dating back to the 11th century.

Margaret was born in 1394, the daughter of Francis of Baux and his third wife Sueva Orsini.

Her paternal grandparents were Bertrand III of Baux, Count of Andria and Squillace, and Marguerite d'Aulnay, and her maternal grandparents were Nicolo Orsini, Count of Nola, Senator of Rome (27 August 1331 – 14 February 1399), and Jeanne de Sabran (1296 - 1375).

On 8 May 1405, Margaret married Peter of Luxembourg, Count of Saint-Pol,[3] of Brienne, and of Conversano (1390 – 31 August 1433), the eldest son of John of Luxembourg, Lord of Beauvoir and Marguerite of Enghien, Countess of Brienne and of Conversano, Heiress of Enghien.

His younger brother John II of Luxembourg, Count of Ligny, an ally of the English during the Hundred Years War, received Joan of Arc as his prisoner, and subsequently sold her to the English, for 10,000 livres.