Until 1772 Biella was under the jurisdiction of the Archdiocese of Vercelli. In that year Pope Clement XI, at the request of Charles Emmanuel III of Sardinia, established the Diocese of Biella by the papal bullPraecipua. The first bishop was Giulio Cesare Viancini, formerly Archbishop of Sassari in Sardinia. In 1803 Napoleon suppressed the diocese, which again fell under the jurisdiction of Vercelli, but was re-established in 1817 by Pope Pius VII who appointed as bishop the Observant Franciscan, Bernardino Bollati. In the shrine of Maria Santissima d'Oropa, situated on a mountain near Biella, the diocese preserves a memorial of St. Eusebius of Vercelli, who was banished to the Orient by Emperor Constantius for his defence of Catholicism against Arianism. St. Eusebius, according to tradition, upon his return from the East, is said to have brought three pictures of the Madonna painted on cedar wood, one of which, the image of Oropa, he placed in a small oratory he had built. In the tenth century the chapel was placed in charge of the Benedictines. When they abandoned the place, Pope Pius II, in 1459, made over the shrine to the Chapter of the Collegiate Church of San Stefano, now the Biella Cathedral, to which it has since belonged. In the sixteenth century, the inhabitants of Biella, in thanksgiving for their deliverance from the plague, built a church over the chapel. In the seventeenth century construction of the devotional complex known as the Sacro Monte di Oropa began. Among the religious edifices of the city of Biella, the most notable is the Gothic cathedral, built in 1402. Its beautiful choir is by Galliari. The baptistery, in the form of a small temple, is said to be an ancient Roman edifice. It is in fact a work of the eleventh century, erected on the site of a Roman tomb. The Chapter of the Cathedral is far older than the Cathedral itself. The Canons of the Collegiate Church of San Stefano appear already in the twelfth century. The Chapter was composed of a Provost, a Treasurer and a Primicerius, among a total of twenty canons. There were also twelve chaplains.
The diocese, which covers an area of 900 km², is divided into 114 parishes. All but one are in the civil Province of Biella, the other falls within Province of Vercelli. A list of parishes by province and commune follows; locations within a commune are shown in brackets.
