A seminary was established in 1880, graduating a small group of priests in 1885, who made the first pilgrimage to Stiklestad in hundreds of years.

On 10 April 1931, the Roman Catholic Apostolic Vicariate of Norway was divided into three jurisdictions, originally two mission sui iuris (missions in areas with very few Catholics, often desolate or remote) and a marginally more populated apostolic vicariate.

Over the remainder of the 20th century, as the Catholic population grew in these areas, and as transportation infrastructure overcame some of the remoteness, these jurisdictions have advanced through apostolic prefecture, apostolic vicariate, two have grown to territorial prelature, and one jurisdiction has grown to become a full diocese.

In 1989, Pope John Paul II visited Trondheim and held an ecumenical service in the Church of Norway's Nidaros Cathedral, as well as a Catholic mass at a nearby sports facility.

In 1993, the Church of Norway authorized a full Catholic mass to be held in the Nidaros Cathedral, for the first time since the 1537 Reformation.