On 31 May 1451, King Afonso V gave João Rodrigues da Costa, son of Rui Galvão, his secretary and knight of his house, an annual pension of 5,000 reals of silver for his studies.

In 1451 he traveled to Italy as chaplain to the Infanta Leonor, sister of King Afonso V of Portugal, who was about to marry Frederick III, Holy Roman Emperor.

On 18 March 1462, King Afonso V authorised the Apostolic Legate João Galvão, Bishop of Coimbra, to carry out what he had been commissioned to do by the Pope Pius II.

On 18 August 1472, King Afonso V appointed João Galvão, Bishop of Coimbra and Count of Santa Comba, a member of his Council and already his Clerk of the Purity, to the post of Chief Intendant of the Kingdom's Works and Lord Mayor of the Counties' Bags of Beira e Ribacoa.

Afonso Álvares Nogueira, who transcribed the Letter of Grant of this title, adds: "And yet ~before this some~us prelates of this see had been called Counts of Santa Comba it was by .m.