She was born on 9 February 1313. Maria became Queen consort of Castile upon her marriage to Alfonso XI in 1328. She was the mother of Pedro of Castile. The relationship between Maria and Alfonso was unhappy: from 1327 before their marriage, Alfonso had a relationship with Leonor Núñez de Guzmán. In 1335, Maria returned to her father in Évora, who demanded that Alfonso separated from Leonor by use of alliances with the Pope, the Muslims and rebels inside Castile, and finally by an invasion. In the peace treaty of Seville in July 1340, Alfonso agreed to have Leonor imprisoned in a convent. At the death of Alfonso 26 March 1350, Maria secured a power position by exerting influence upon the leader of her son's council, Juan Alfonso de Alburquerque. She participated in the rebellion against her son in 1354, and turned over Toro to the rebels, which caused his imprisonment. After this, she returned to Portugal.