Born in Castile to a noble family, he was appointed archbishop of Santiago in 1460. However he temporality shared power with his uncle, Alonso I de Fonseca, the Archbishop of Seville, who put an end to the situation of conflict que in Santiago following the destruction of the castle and the agitated archbishopric of Rodrigo de Luna.
The following year he must take actual possession of his office although he refused to leave Seville, hence the idiom: «quen foi a Sevilla, perdeu a silla» (meaning: he who goes to the fair, loses his chair). In 1462 he was imprisoned in Vimianzo and must go into temporary exile. Finally, he governed the archbishopric of Santiago until 1507.
He was one of the key figures of the nobility siding against the Irmandiños, and the last archbishop with military might. As far as construction works, he commissioned the cathedral’s Torre do Estribo, today the Clock Tower, and some palace in the city. He completed the destruction of the castle of Rocha Forte, following the Irmandiño attack by using its ashlars to build the castle of Pico Sacro.