The Diocese of Duvno (Latin: Dioecesis Dumnensis; Dioecesis Dalminiensis; Croatian: Duvanjska biskupija) was a Latin rite particular church of the Catholic Church that was established in the 14th century with a seat in present-day Tomislavgrad in Bosnia and Herzegovina. It was a suffragan diocese of the Archdiocese of Split, and during the 17th century of the Archdiocese of Dubrovnik. The diocese consisted of four parishes: Roško Polje, Duvno, Posušje and Rama.
The diocese was established under the patronage of the Šubić family. The seat of the diocese was in the former fortress of Rog, located in present-day Roško Polje near Tomislavgrad, and the cathedral church was the Church of St. John the Baptist. Due to the Ottoman incursions in the diocese from the 1460s to the final conquest of the diocese in the 1480s, the bishops of Duvno resided on the territory of the Archdiocese of Split. Vid of Hvar, who ruled the diocese until 1507, was the last bishop active in the diocese until 1551. Until that time, the diocese was nominally held by titular bishops, followed by a line of the so-called missionary bishops, the first of whom was Daniel Vocatius. The missionary bishops resided in the Ottoman territory, in the Franciscan friary in Rama, which belonged to the diocese of Duvno, but after its destruction by the Ottomans in the late 17th century, they continued to administer the diocese from the Archdiocese of Split, while they were helped by the Illyrian priests and the Bosnian Franciscans who lived under the Ottomans. From 1610 to 1645, the diocese was again ruled only nominally by titular bishops, and after that, by the missionary bishops and the bishops of the neighbouring Makarska. From 1800, the title of the bishop of Duno was only titular until 1881, when the diocese was incorporated into the newly established Diocese of Mostar-Duvno after Austria-Hungary occupied the Ottoman-held Bosnia and Herzegovina.