Berengaria was born in either 1179 or 1180 in Burgos as the eldest daughter of Alfonso VIII of Castile and Eleanor of England. She would be one of 11 siblings, and she was heir presumptive for several years until the birth of subsequent younger brothers. However, many died in childhood, and of her male siblings, only her youngest brother Henry was alive when her father died.
Perhaps anticipating this, Berengaria was a much sought after bride in Europe. She was first betrothed to Conrad, Duke of Rothenburg but they never saw each other. By 1191 Berengaria requested an annulment of the betrothal from the pope. Conrad was assassinated in 1196, and Berengaria was free to remarry.
In a political alliance with León Berengaria married her first cousin once removed, Alfonso IX of León. Alfonso had been married once before, to Theresa of Portugal, with whom he had a son, Ferdinand, who died childless around the age of 22 and Sancha and Dulce of León. Berengaria and Alfonso IX had five children, of whom one died young, and one became a nun.
In 1198, Pope Innocent III objected to the marriage on the grounds of consanguinity. They sought dispensation, which was not granted. They stayed together until 1204 and did manage to have their children declared legitimate. Berengaria returned to Castile in 1204, with her children.
In 1214, Berengaria’s father died, and he was succeeded by her ten-year-old brother Henry I. Their mother Eleanor assumed the regency but died suddenly 24 days later. Berengaria now replaced her as regent. Her life changed again on 6 June 1217 when Henry died suddenly after being hit in the head with a tile that had come loose.
She feared her former husband as a threat to her reign, as he was her brother’s closest agnate heir and innocently wrote to Alfonso asking that their eldest son Ferdinand be allowed to visit her and then abdicated in his favour on 31 August 1217. She realised she would never be able to be the military leader that Castile needed. Despite her brief personal reign Berengaria continued to be her son’s closest advisor. She arranged his marriage to Elisabeth of Hohenstaufen, which took place on 30 November 1219. She prevented the marriage of John of Brienne to her former husband’s eldest daughter Sancha, by quickly arranged his marriage to her own daughter, also named Berengaria.
In 1230, her former husband died, and he designated his daughters Sancha and Dulce as his heirs, superseding the rights of her son. She met with Theresa of Portugal and succeeded in ratifying the Treaty of Las Terceríasm by which the sisters renounced their claim to the throne in exchange for a substantial sum of money and other benefits. Ferdinand thus united the thrones of León and Castile. She once again played matchmaker when Elisabeth of Hohenstaufen died and concerned with her son’s virtue; she chose a French noblewoman, Jeanne of Dammartin as his new wife.
She last saw her son in 1245 and died on 8 November 1246 at the age of 66.