Following 38 years as a priest, he was elevated to the episcopate by the then Patriarch of Babylon of the Chaldeans, Mar Raphael I Bidawid.
Born to an Assyrian family from Baghdad, he attended the Chaldean Patriarchal Seminary in Mosul for formation and left to Rome at the age of 17.
In 1977, he was made associate pastor of Mother of God parish in Southfield, Michigan, where he would serve with Mar George Garmo.
[2] In 2002, Pope John Paul II created a second diocese for the Chaldean Catholic Church in the United States.
Mar Sarhad Jammo would be given an apostolic seat to preside over the Eparchy of St. Peter the Apostle covering the western United States.
The St. Peter Diocese has been the first to implement the reformed mass showing Bishop Jammo's passion and zeal for liturgical renewal.
[2] Bishop Jammo is an established author and historian of the Chaldean Catholic history, liturgy, and language.