Bishop Jamnik was born into a Roman Catholic family in the capital of Slovenia, but spent his childhood in a peasant family in the village of Videm, Dobrepolje of the historical region of Lower Carniola.

[1] After finishing primary school in Grosuplje in 1976, Anton graduated a Josip Jurčič Gymnasium in Stična with the secondary education during 1976–1980 and also served his compulsory military service in the Yugoslav Army (1980–1981).

Jamnik was engaged in pastoral work and served as priest in Kočevje parish from 1987 until 1990, and from 1990 to 1994 he was a personal assistant of the Archbishop of Ljubljana.

In the same year he moved to the Institute of St. Stanislav, where he taught religion and later philosophy at the Diocesan Classical Gymnasium.

Since 1997 he has been an assistant professor of philosophy at the Faculty of Theology, University of Ljubljana, and in 2012 he was elected and appointed associate professor of philosophy at the Faculty of Theology, University of Ljubljana.