The Diocese of Lucera-Troia (Latin: Dioecesis Lucerina-Troiana) is a Roman Catholic bishopric in Apulia, in southern Italy, with its episcopal seat at Lucera Cathedral. The present diocese was formed in 1986 by combining the older diocese of Lucera with the diocese of Troia, the seat of which was Troia Cathedral, now a co-cathedral of the united diocese.
Local tradition traces the origin of the bishopric of Lucera to the third century and Saint Bassus. The first historically certain bishop is Marcus (c. 743).
In 1391, the diocese of Lucera was increased by the addition of the bishopric of Castel Fiorentino (Farentino), a city founded in 1015 by the Byzantine catapanBasil Mesardonites, and the place of Emperor Frederick II‘s death.
In 1818, the united dioceses of Montecorvino and Vulturaria were added to Lucera. Motta Montecorvino had gained a bishopric in the tenth century, counting among its bishops Saint Albert of Montecorvino. It was joined to that of Vulturaria in 1433, although it too continues to give its name to a titular diocese.
On September 30, 1986, the diocese of Troia was united with Lucera to form the diocese of Lucera–Troia as a suffragan of the also renamed Metropolitan Archdiocese of Foggia-Bovino. Both its cathedral in Lucera and its co-cathedral in Troia have the rank of minor basilica.