The Diocese of Qui Nhơn (also written as the Diocese of Quy Nhơn; Latin: Dioecesis Quinhonensis; Vietnamese: Giáo phận Qui Nhơn) is a Catholic diocese in central Vietnam. The Bishop is Matthieu Nguyễn Văn Khôi, previously rector of Assumption Cathedral in Quy Nhơn and professor at the Stella Maris Major Seminary of Nha Trang, was appointed Coadjutor Bishop of the diocese by Pope Benedict XVI on December 31, 2009. The creation of the diocese in present form was declared on 24 November 1960.

The diocese covers an area of 16,200 km², and is a suffragan diocese of the Archdiocese of Huế.

By 2004, the diocese of Qui Nhơn had about 62,520 Catholics (1.7% of the population), 70 priests and 36 parishes.

Assumption Cathedral in Quy Nhơn town has been assigned as the cathedral of the diocese.

Vicar Apostolic			Period in office	Status	Reference
1		Bishop Pierre Lambert de la Motte, M.E.P.	July 29, 1658 – June 15, 1679	Died in office
2		Bishop Guillaume Mahot, M.E.P.	January 29, 1680 – June 04, 1864
3		Bishop Joseph Duchesnes	1864 – June 17, 1864
4		Bishop François Perez	February 05, 1687 – September 20, 1728
5		Bishop Alexandre de Alexandris, B.	September 20, 1728 – September 13, 1738
6		Bishop Valère Rist, O.F.M.	1737 – April 13, 1743
7		Bishop Arnaud-François Lefèbvre, M.E.P.	October 06, 1741 – March 27, 1760
8		Bishop Guillaume Piguel, M.E.P.	July 29, 1762 – June 21, 1771
9		Bishop Pierre-Joseph-Georges Pigneau de Béhaine, M.E.P.	September 24, 1771 – October 09, 1799
10		Bishop Jean Labartette, M.E.P.	October 09, 1799 – August 06, 1823
11		Bishop Jean-Louis Taberd, M.E.P.	September 18, 1827 – July 31, 1840
12		Bishop Étienne-Théodore Cuenot, M.E.P.	July 31, 1840 – March 02, 1844	Remained as Vicar apostolic of Eastern Cochin.

Coadjutor Vicar Apostolic of Cochin

Vicar Apostolic			Period in office	Reference
1		Bishop Charles-Marin Labbé, M.E.P.	January 15, 1697 – March 24, 1723
2		Bishop Alexandre de Alexandris, B.	December 22, 1725 – September 20, 1728
3		Bishop Valerian Rist, O.F.M.	October 03, 1735 – September 15, 1737
4		Bishop Edmond Bennetat, M.E.P.	September 22, 1745 – July 16, 1758
5		Bishop Jean Labartette, M.E.P.	March 30, 1784 – October 09, 1799
6		Bishop Jean-André Doussain, M.E.P.	July 23, 1798 – December 14, 1809
7		Bishop Pierre-Marie Le Labousse, M.E.P.	1801 – May 28, 1801
8		Bishop Jean-Joseph Audemard	1817 – August 08, 1821
9		Bishop Étienne-Théodore Cuenot, M.E.P.	September 09, 1831 – July 31, 1840
10		Bishop Dominique Lefèbvre, M.E.P.	December 10, 1839 – March 02, 1844

Vicar Apostolic			Period in office	Status	Reference
13		Bishop Étienne-Théodore Cuenot, M.E.P.	March 02, 1844 – November 14, 1861	Died in office, Martyred.
14		Bishop Eugène-Étienne Charbonnier, M.E.P.	September 09, 1864 – August 07, 1878	Died in office
15		Bishop Louis-Marie Galibert, M.E.P.	May 23, 1879 – April 24, 1883
16		Bishop Désiré-François-Xavier Van Camelbeke, M.E.P.	January 15, 1884 – November 09, 1901
17		Bishop Damien Grangeon, M.E.P.	June 09, 1902 – December 03, 1924	Remained as Vicar apostolic of Quinhon.

Coadjutor Vicar Apostolic of Eastern Cochin (1844-1921)

Vicar Apostolic		Period in office	Reference
11	Bishop François-Marie-Henri-Agathon Pellerin, M.E.P.	March 11, 1844 – August 27, 1850
12	Bishop Constant Philomen Jeanningros, M.E.P.	August 24, 1911 – March 21, 1921

Vicar Apostolic		Period in office	Status	Reference
18	Bishop Damien Grangeon, M.E.P.	December 03, 1924 – March 03, 1929	Resigned
19	Bishop Augustin-Marie Tardieu, M.E.P.	December 19, 1929 – December 12, 1942	Died in office
20	Bishop Paul-Raymond-Marie-Marcel Piquet, M.E.P.	November 11, 1943 – July 05, 1957	Transferred to Nha Trang.

Bishop			Coat of Arms	Period in office	Status	Reference
1		Bishop Pierre-Marie Phạm Ngọc Chi		November 24, 1960 – January 18, 1963	Transferred to Da Nang.
2		Bishop Dominique Hoàng Văn Ðoàn, O.P.		January 18, 1963 – May 20, 1974	Died in office
3		Bishop Paul Huỳnh Ðông Các		July 01, 1974 – June 03, 1999	Resigned
4		Bishop Pierre Nguyễn Soạn		June 03, 1999 – June 30, 2012
5		Bishop Matthieu Nguyễn Văn Khôi		June 30, 2012 – present	Incumbent

Coadjutor Bishops of Qui Nhon (1976-2012)

Coadjutor Bishop			Coat of Arms	Period in office	Reference
1		Bishop Joseph Phan Văn Hoa		March 30, 1976 – October 06, 1987
2		Bishop Matthieu Nguyễn Văn Khôi		December 31, 2009 – June 30, 2012

13°46′31″N 109°14′06″E / 13.7752°N 109.2350°E / 13.7752; 109.2350