Cardinal Kim Sou-hwan was born on May 8, 1922 in Daegu, Korea into a devout Catholic family. His grandfather was martyred by being starved to death in prison because of his faith while his parents - his father Kim Young-seok (Joseph) and his mother Seo Jung-ha (Martina) - passed on the faith to their children, cultivating the hope that one of them would consecrate themselves to God. Thanks to his mother's sacrifices, Kim Sou-hwan and his brother, Dong-hwan, were able to devote themselves to their studies and become priests. In 1944, close to graduation, Kim Sou-hwan was forcibly enlisted as a student-soldier by the Japanese imperial government. After the end of the war, Kim Sou-hwan returned to his studies and in early 1947, he was transferred to what is now the College of Theology at the Catholic University of Korea. On September 15, 1951 in Daegu he was ordained a priest in the Cathedral of Gyesan-dong. 

Fr. Kim Sou-hwan began his first pastoral ministry as a parish priest in Andong and in April 1953, he became secretary of the diocesan bishop of Daegu, Monsignor John Baptist Choi Deok-hong. In July 1956, he went to study at the University of Münster, Germany where he specialized in theology and sociology. In 1964, he returned to Korea and was appointed president of the Catholic Times in June of that same year. On February 15, 1966 Fr. Kim Sou-hwan, was consecrated bishop at only 44 years-old, being the first diocesan bishop of the Diocese of Masan where his pastoral motto was "for you and for many" (pro vobis et pro multis).

As the first diocesan bishop, Monsignor Kim Sou-hwan sought to form his diocese, according to the spirit of renewal in the Church proposed by the Second Vatican Council, making him the Vice President of the Catholic Episcopal Conference of Korea and the Vice Representative for Korea at the Synod of Bishops. In April 1968, he was appointed the twelfth archbishop of the Archdiocese of Seoul. On March 28 of the following year, Archbishop Kim Sou-hwan was appointed Cardinal by Saint Paul VI at 47 years of age, bearing the title under the Church of Saint Felix from Cantalice in the roman neighborhood of Centocelle. Cardinal Kim Sou-hwan served as diocesan bishop for the Archdiocese of Seoul for the next thirty years as the president of the Korean Episcopal Conference, as well as being the Apostolic Administrator for the Diocese of Pyongyang since June 1, 1975. 

In Seoul, Cardinal Kim Sou-hwan laid down the principles of renewal and participation of the Church in the concrete reality of its time according to the spirit of the Second Vatican Council. He became a human rights advocate expressing a deep interest in the poor and oppressed, worked for overseas missions and for the North Korean people by promoting exchanges between the churches of South and North Korea. He was assigned the task of improving the state of the Catholic Church in Korea during the 44th International Eucharistic Congress in 1989.

In 1997 at the age of 75, Cardinal Kim Sou-hwan resigned as diocesan bishop but his request was not accepted. After renewing his resignation, Saint John Paul II accepted it on May 29, 1998. When Kim Sou-hwan was appointed Bishop of Seoul, the number of faithful among 48 parishes in the archdiocese was 140,000. When he left the archdiocese, that number reached 1,210,000 throughout 197 parishes and the number of priests rose to 590.

The social doctrine of Cardinal Kim Sou-hwan was aimed at seeking for the common good based on a firm appreciation of human dignity. Rooted in his thoughts, all social structures and political systems had to move towards the common good stressing that the Church should refuse to compromise with injustice. The Cardinal sought to restore the human rights of those who had been politically oppressed under the regime of the 1970s and to assist the democratization movement of the 1980s. 

Cardinal Kim Sou-hwan was always a friend of the poor and marginalized. Being a good-hearted man, he met disabled people and prisoners and visited the poor who had lost their homes, as well as fighting for the rights and interests of farmers and laborers. He was particularly concerned about what the Catholic Church could do for the poor and founded a pastoral committee dedicated to helping them, which, for the past three decades, led to the increase in the number of social structures in their favor. 

Once he withdrew from pastoral work in the government, Cardinal Kim Sou-hwan visited the prisoners on death row and celebrated mass at the Seoul Detention Center in Uiwang-si. In April 2005, after the death of Saint John Paul II, he could no longer vote in the conclave due to age restrictions, however he was able to concelebrate with two others at the inaugural mass of the pontificate of Benedict XVI. 

He died on the afternoon of February 16, 2009 at St. Mary's Hospital in Seoul, leaving the Korean Church and other religious denominations in tears. The official figures reported that 387,000 people paid homage to him at the funeral, while the grieving faithful who visited the Cathedral of Myeongdong formed a procession of over three kilometers. His body was buried in the Catholic priests' cemetery in the city of Yongin, and his tomb is visited by hundreds of people every day. Cardinal Kim Sou-hwan's pastoral motto is carved in Korean and Latin on the tombstone, and his epitaph is taken from Psalm 23: "The Lord is my shepherd, there is nothing I lack."