She was the daughter of Hugh X de Lusignan, "le Brun", Seigneur de Lusignan, Count of La Marche and Isabella of Angoulême, queen dowager of England.
Isabella was betrothed by the treaty of Vendôme in March 1227 to Alfonso, Count of Poitiers, the third surviving son of Louis VIII of France and Blanche of Castile.
[2] The marriage contract was however broken off and Alfonso instead married Joan, Countess of Toulouse.
They had the following children: A charter dated October 1252 records a dispute with Isabella and her husband's will.
Isabella was granted a payment by her half-brother King Henry III in 1254.