Joan was married in October 1196, at Rouen, as his third wife, to Raymond VI, Count of Toulouse, with Quercy and the Agenais as her dowry. She was the mother of his successor Raymond VII of Toulouse (born July 1197), and a daughter, Joan (born 1198), who married Bernard II de la Tour, Lord of la Tour.
Some chroniclers, who disliked Raymond VI, Count of Toulouse (believing he was a heretic), claim that his marriage to Joan quickly became unhappy, and that she had been fleeing to her brother Richard's domains in 1199, when she learned of Richard's death. "The Chronicle of Guillaume de Puylaurens", however, says the following of Joan's last few months: "She was an able woman of great spirit, and after she had recovered from childbed, she was determined to counter the injuries being inflicted upon her husband at the hands of numerous magnates and knights. She therefore took arms against the lords of Saint-Felix, and laid siege to a castrum belonging to them known as Les Cassés. Her efforts were of little avail; some of those with her treacherously and secretly provided arms and supplies to the besieged enemy. Greatly aggrieved, she abandoned the siege, and was almost prevented from leaving her camp by a fire started by the traitors. Much affected by this injury, she hastened to see her brother King Richard to tell him about it but found that he had died. She herself died, whilst pregnant, overcome by this double grief."