Cardinal Rosales has served as prefect of discipline and as rector of the Minor Seminary of Lipa and as parish priest.
On 12 August 1974 he was appointed titular Bishop of Oescus and Auxiliary of Manila, and on 28 October of the same year he received episcopal ordination. During this time he served as rector of San Carlos Seminary in Makaty and was president of the Commission for Seminaries of the Philippines Bishops’ Conference.
On 9 June 1982 he was appointed Coadjutor Bishop of Malaybalay, and on 14 September 1984 he was made Bishop of the diocese. He wa appointed Archbishop of Lipa on 30 December 1992.
Within the Philippines Bishops’ Conference he served as vice-president of the Permanent Council and later as president of the Episcopal Commission for the Clergy.
On 15 September 2003, Cardinal Rosales was appointed Archbishop of Manila. His resignation was accepted on 13 October 2011.
He was member of Council of Cardinals for the Study of Organizational and Economic Affairs of the Holy See
Created and proclaimed cardinal by Benedict XVI in the consistory of 24 March 2006, of the Title of Santissimo Nome di Maria a Via Latina (Most Holy Name of Mary in Via Latina).