Berengaria was queen regnant of Castile in 1217 and queen consort of León from 1197 to 1204. As the eldest child and heir presumptive of Alfonso VIII of Castile, she was a sought after bride, and was engaged to Conrad, the son of Holy Roman Emperor Frederick I Barbarossa. After his death, she married her cousin, Alfonso IX of León, to secure the peace between him and her father. She had five children with him before their marriage was voided by Pope Innocent III.
When her father died, she served as regent for her younger brother Henry I in Castile until she succeeded him on his untimely death. Within months, she turned Castile over to her son, Ferdinand III, concerned that as a woman she would not be able to lead Castile's forces. However, she remained one of his closest advisors, guiding policy, negotiating, and ruling on his behalf for the rest of her life. She was responsible for the re-unification of Castile and León under her son's authority, and supported his efforts in the Reconquista. She was a patron of religious institutions and supported the writing of a history of the two countries.