In 1221 at Ágreda, Eleanor married King James I of Aragon; she was nineteen and he was fourteen.

[5] Eleanor's marriage to James was annulled in 1230, and the agreement prohibited her from remarrying.

She went to the Abbey of Santa María la Real de Las Huelgas to join her elder sister Berengaria who had retired from ruling Castile and Leon, and their other sister Constance, who was long a nun there.

During work on the monastery in the middle of the twentieth century it was found that the remains of Eleanor, mummified and in good condition, lay in her tomb of limestone; the roof had two slopes and was smooth, although in the past was polychrome.

Her coffin was wooden and devoid of cover, although there were still remnants of its shell and lysed cross made of studded gold braid, as well as clothing that was buried with the queen, among which highlighted three brocade garments in Arabic, which Manuel Gómez Moreno considered similar to those found in the grave of her grandnephew Philip.