The Mission of Mysore was separated from the Vicariate Apostolic of Pondicherry on March 16, 1845, to become first a pro-Vicariate, and then in 1850 a Vicariate Apostolic entrusted to Msgr Charbonnaux who was, till then, Co-adjutor to the Bishop of Pondicherry.

In 1886, the Vicariate of Mysore was elevated to a Diocese, and its Vicar Apostolic, Msgr Coadou became its First Bishop, residing, however, in Bangalore. Untill 1940, the Diocese of Mysore included the entire districts of Mysore, Coorg and Kollegal, but on February 13, 1940, by the Apostolic Letter "Felicius Increscente" of Pius XII, Bangalore was separated from Mysore and the Bishop of former Mysore Diocese Bp M.B. Despatures became the Bishop of Bangalore, comprising the districts of Bangalore, Kolar, Tumkur and Chitradurga.

The Diocese of Mysore (as distinct from Bangalore) was reconstituted in 1941 with the addition of the Nilgiris district and part of the Coimbatore district.

However 15 years later, on July 3, 1955, by the Apostolic Constitution "Nuntiatur in Psalmis" of Pope Pius XII, these districts of Nilgiris and Coimbatore were again separated from Mysore and erected into Diocese of Ootacamund (Ooty) in Tamil Nadu.

On November 16, 1963, by the Apostolic Constitution "Indicae Regionis Conditio" of Pope Paul VI, three most districts, Chikmagalur, Hassan, Shimoga, were separated from the Mysore Diocese to form the Diocese of Chikmagalur.

The present Diocese of Mysore comprises the four districts of Mysore, Mandya, Coorg & Chamarajanagara. It is surrounded by the Archdiocese of Bangalore, Diocese of Ooty, Calicut, Mangalore and Chikmagalur.

Name	Designation	Period
Most Rev. Joseph Roy	Bishop	1994-2003
Most Rev. Francis Michaelappa	Bishop	1986-1993
Most Rev. Eugène-Louis Kleiner, M.E.P.	Bishop	1980-1910
Most Rev. Sebastiäo Francisco Mathias Fernandes	Bishop	1963-1985
Most Rev. René-Jean-Baptiste-Germain Feuga	Apostolic Administrator	1962-1963
Most Rev. Vincent D’Souza	Auxiliary Bishop	1959-1961
Most Rev. René-Jean-Baptiste-Germain Feuga	Bishop	1941-1962
Most Rev. Maurice-Bernard-Benoit-Joseph Despatures,	Bishop	1922-1940
Most Rev. Hippolyte Teissier, M.E.P.	Bishop	1916-1922
Most Rev. Augustin-François Baslé, M.E.P.	Bishop	1910-1915
Most Rev. Jean-Yves-Marie Coadou, M.E.P.	Bishop	1886-1890
Most Rev. Jean-Yves-Marie Coadou, M.E.P.	Apostolic Administrator	1880-1886
Most Rev. Joseph-Auguste Chevalier, M.E.P.	Apostolic Administrator	1873-1880
Most Rev. Etienne-Louis Charbonnaux, M.E.P.	Apostolic Administrator	1850-1873