He was ordained a priest by Cardinal Justinus Darmojuwono on 3 December 1975 as a member of the Society of Jesus, better known in the Western World as Jesuits.

[3] On 10 May 2000, it was announced that Sunarko had been nominated as the bishop of Purwokerto, succeeding Paschalis Soedita Hardjasoemarta who had died in May of the previous year.

On 8 September of that year Sunarko was ordained bishop of the Diocese of Purwokerto by Cardinal Darmaatmadja.

[1] On 29 December 2016, Sunarko officially retired as the bishop of Purwokerto and submitted his letter of resignation to the Pope, four days after his 75th birthday.

[1] He was succeeded by Christophorus Tri Harsono, who was ordained bishop of Purwokerto on 16 October 2018.