Bishop Janjić was born into a Bosnian Croat Roman Catholic family of Ante and Jela in Bosanska Posavina as their first child.
After graduation from schools in his native Vidovice and Orašje, he was admitted to the minor seminary in 1959, consequently joined the Major Theological Seminary in Split in 1963,[1] and was ordained as priest on June 29, 1969 for the Roman Catholic Diocese of Kotor,[2] after completed his philosophical and theological studies.
Janjić served as parish administrator in Muo, Škaljari, Gornji Stoliv, Budva, Prčanj and Herceg Novi.
Last years before his nomination to the bishophood he was a Canon of the Cathedral of Saint Tryphon and Dean of Herceg Novi.
[1] On March 11, 1996, he was appointed by Pope John Paul II as the Diocesan Bishop of the Roman Catholic Diocese of Kotor.