He was ordained to the priesthood by Archbishop Luigi Traglia on 20 December 1952, and then taught dogmatic theology at the Luanda seminary and served as chief editor of the Catholic newspaper O apostolado ("The apostolate") until 1956, whence he became preacher of the cathedral.

Whilst in Portugal, he did pastoral work, served as a counselor to the Movement of Teams of Our Lady, and studied civil law at the Classical University.

Upon returning to Angola in 1971, he taught moral theology at the Pius XII Institute of Social Sciences, and served as an official of the archdiocesan curia of Lubango, secretary general of the Angolan Cáritas, and special assistant to students and former political prisoners.

Archbishop do Nascimento was kidnapped by guerrillas during a pastoral visit on 15 October 1982; he was later freed on 16 November of that same year after Pope John Paul II made an appeal for his release.

On 4 June 2015, he made his profession in the Priestly Fraternities of Saint Dominic to the Promoter for the Laity of the Order of Preachers, Rui Carlos Antunes e Almeida Lopes.