Jaime Lachica Sin studied philosophy and Catholic theology in Jaro and received on April 3, 1954, the sacrament of Holy Orders. He was then appointed for three years to diocesan missionary of the Diocese of Capiz. From 1957 to 1967 he headed to it as the first rain, dean and professor, the Seminary of St. Pius X in Roxas City. Pope Paul VI. appointed him on 10 February 1967 Titular Bishop of Obba and auxiliary bishop in the Archdiocese of Jaro. He received his episcopal consecration of the Bishop of Capiz, Antonio Frondosa, on 18 March of the same year.
On January 15, 1972, he was first appointed Titular Archbishop of Massa Lubrense and Koadjutorerzbischof in the Archdiocese of Jaro, but already followed on 8 October of the same year as Supreme Pastor of the Archdiocese to his deceased predecessor Jose Maria Cuenco. On 21 January 1974 he was finally appointed Archbishop of the Archdiocese of Manila. Paul VI. took Jaime Lachica Sin on May 24, 1976 as cardinal priest with the titular church of Santa Maria ai Monti in the College of Cardinals to. In the conclaves of August and October 1978, he was the youngest participant. From 1977 to 1981 he served as Chairman of the Philippine Bishops' Conference.
In 1986, he actively supported the EDSA Revolution, by calling for non-violent resistance against the advancing troops of Ferdinand Marcos. In addition to his administrative obligations Jaime L. Sin committed for the long term interests of patient care and Caritas. He campaigned for ecumenism and invited the first Filipino Archbishop Protestants, Muslims and representatives of other Christian denominations not to a joint discussions.
For health reasons, Sin not participated in the conclave for the election of Benedict XVI. , The successor of John Paul II in part.
On 21 June 2005 he died at the Cardinal Santos Medical Centre to organ failure.