The Diocese of Trivento (Latin: Dioecesis Triventinus) is a Latin Church ecclesiastical territory or diocese of the Catholic Church in Italy.

The Diocese of Trivento is a suffragan diocese in the ecclesiastical province of the metropolitan Archdiocese of Campobasso-Boiano, in the ecclesiastical region of Abruzzo-Molise, southern Italy.

Nazario, Celso e Vittore, dedicated to the diocesan patron saints St. Nazarius, St. Celsus and St. Victor, in the episcopal see of Trivento, Campobasso province, in Molise administrative region.

The other major sanctuary is at Canneto, in the commune Roccavivara, founded in the fourth century and until the tenth dependent on Montecassino.

According to local legend the earliest bishop of Trivento was St. Castus of an uncertain epoch, assigning him to the fourth century.