The Most Reverend Alphonse Nguyễn Hữu Long was appointed bishop on December 22, 2018.

[6] The circuit (trấn) of Nghệ An was evangelized by Jesuit missionaries as early as in 1629, especially by Girolamo Maiorica.

After the Apostolic Vicariate of Tonkin (Đàng Ngoài) was created in 1659, MEP missionaries were assigned to Nghệ An trấn.

In 1846, the Vicariate of South Tonkin (Nam Đàng Ngoài) was established, covering the area of Nghệ An and Hà Tĩnh provinces as well as northern Quảng Bình province.

In 2006, the other part of Quảng Bình province, south of Gianh River and Son River, was officially transferred from Archdiocese of Huế to the Diocese of Vinh after decades under Vinh's de facto supervision following the Partition of Vietnam.