[2] After being ordained, Buenaventura was named chaplain and grand almoner of King Charles III of Spain.

He was consecrated as bishop in the Royal Church of San Jerónimo, Madrid on 28 June 1761 by Manuel Quintano Bonifaz, Titular Archbishop of Pharsalus and Inquisitor general for Spain.

[4] As patriarch, he replaced Álvaro de Mendoza Caamaño Sotomayor, who had died on 23 January 1761.

[4] As cardinal-priest he replaced Lorenzo (Giovanni Vincenzo Antonio) Ganganelli, who had been elected as Pope Clement XIV.

[2] He was replaced as Patriarch of the West Indies by Francisco Javier Delgado Venegas, who was appointed on 30 March 1778.

[5] He was replaced as cardinal-priest by Giovanni Battista Bussi de Pretis, who was appointed on 12 September 1794.