After studying sociology in Hong Kong, he was ordained to the priesthood by Archbishop Paul Roh Ki-nam on 18 March 1961 at the Myeongdong Cathedral in Seoul.

[1] Cheong then did pastoral work in Seoul until becoming a professor at its minor seminary and notary of its archdiocesan curia in 1962.

[2] He received his episcopal consecration on the following 3 October from Archbishop Kinam Ro, with Bishops James Pardy, MM, and Peter Han Kong-ryel serving as co-consecrators, in the Church of the Holy Family in Cheongju.

[5] Pope Benedict XVI created him Cardinal-Priest of Santa Maria Immacolata di Lourdes a Boccea in the consistory of 24 March 2006.

By the first week of March, Cheong's condition seemed to improve upon the removal of life-sustaining equipment, barring the intravenous, with reports that his blood pressure and oxygen levels were gradually returning to normal.