"From this moment, the accused has two months in which to make an eventual appeal. The penal trial before the Vatican judicial authorities will continue as soon as the canonical sentence has been made definitive," the Vatican said in a statement.
Wesolowski, originally from Poland, was ordained a priest by Pope John Paul II and served as papal envoy to the Dominican Republic for five years. He was recalled by the church last year following accusations that he had abused boys while stationed in Santo Domingo.
The Vatican tribunal followed a recommendation by the United Nations Committee Against Torture in May for the Holy See to "proceed to a prompt and impartial investigation of Archbishop Wesolowski."
Pope Francis has emphasized his "zero tolerance" approach to clergy sexual abuse.