The powerful influence of his family opened him a public career early in life. He was made archdeacon of Calatrava, and became a member of the king's council while young. In 1338 he was chosen archbishop of Toledo in succession to his uncle by the favour of the king, Alfonso XI of Castile. At the battle of Tarifa he fought against a great invasion from Africa in 1340, and at the taking of Algeciras in 1344 he led the armed levy of his archbishopric.
In 1343 he had been sent to Pope Clement VI at Avignon to negotiate a grant of a tax on the revenues of the Church for the Crusade. His military and diplomatic ability became known to the pope, who made him a cardinal-priest of S. Clemente in 1350. Albornoz left Spain on the death of the king Alfonso XI in that year, and never returned. It has been said, but not on contemporary evidence, that he fled from fear of Pedro of Castile.
Albornoz then moved to the Marche and Romagna against the Malatesta of Rimini and the Ordelaffi of Forlì. The Papal commander Rodolfo II da Varano, lord of Camerino, defeated Galeotto Malatesta, forcing his family to become a loyal ally of the Pope. This was followed by the submission of the Montefeltro of Urbino and the da Polenta of Ravenna, and of the cities of Senigallia and Ancona. Towards the end of 1356 Albornoz was appointed as bishop of Sabina.
Only Giovanni Manfredi of Faenza and Francesco II Ordelaffi of Forlì were at that point resisting the Papal reconquest. Albornoz had managed to submit only the former when he was being recalled in 1357, being replaced by Androin de la Roche, abbot of Cluny. Before leaving, in a meeting with all the Papal vicars held on April 29 1357, Albornoz issued the Constitutiones Sanctæ Matris Ecclesiæ, which regulated all the matters of the Papal States and its division into provinces. They remained effective until 1816.
Albornoz missed only Bologna to complete his rebuilding of the Papal States. When that city was attacked by Bernabò Visconti of Milan, its ruler, Giovanni d'Olleggio, decided to hand it over to Albornoz. In the meantime, Innocent died: the Spanish cardinal refused the tiara, and Urban V was elected. Under him Albornoz started the military campaign against Visconti and, when all attacks failed, Urban proclaimed a crusade against him.
As Urban's greatest desire was that of a crusade against the Turks, the two parts signed a hasty peace, which was highly favourable to Visconti. The relentless work of Albornoz had anyway paved the Urban V to Rome (1367).
As legate, Albornoz showed himself to be an astute manager of men and effective fighter. He began by making use of Cola di Rienzo (former leader of the citizenship freedom in Rome), whose release from prison at Avignon he secured. After the murder of the tribune in 1354 Albornoz pursued his task of restoring the pope's authority by intrigue and force with remarkable success. As a mark of gratitude the pope appointed him legate at Bologna in 1367, but he died at Viterbo the same year. According to his own desire his remains were carried to Toledo, where Henry of Castile had them to be entombed with almost royal honours.
The college of St Clement at Bologna was founded by Albornoz for the benefit of Spanish students.