Kitbunchu was born in Sam Phran, a district of the Nakhon Pathom Province, to a family of Chinese descent and studied at the minor seminary of Si Racha.

He received his episcopal consecration on 3 June 1973 from Archbishop Joseph Khiamsun Nittayo, with Bishops Lawrence Thienchai Samanchit and Michel-Auguste–Marie Langer, MEP, serving as co-consecrators.

[2] Pope John Paul II created him Cardinal-Priest of San Lorenzo in Panisperna in the consistory of 2 February 1983; he was the first cardinal from Thailand.

[citation needed] Kitbunchu was one of the cardinal electors who participated in the 2005 papal conclave that selected Pope Benedict XVI.

He denied funeral Masses to drug traffickers, saying that such people "destroy society" and engage in "acts of indirect murder.