During the reign of His Holiness Pope Gregory XVI the Mysore Mission was separated from the then existing Vicariate Apostolic of Pondicherry on the 16th March, 1845 and was made into a Pro-Vicariate Apostolic. Later in 1850, His Holiness Pope Pius IX erected it into a Vicariate Apostolic and entrusted it to Rt. Rev Msgr. E. L. Charbonneaux, MEP. the co-adjutor Bishop of Pondicherry.
In 1886, when His Holiness Pope Leo XIII established the Indian Ecclesiastical Hierarchy by His Papal Bull “ Humanae Salutis Auctor”, Mysore became a Diocese with Bangalore as its headquarters.
His Holiness Pope Pius XII by his Apostolic Letter “ Felicius Increscente”, dated 13th February 1940, appointed Rt. Rev. Msgr. Rene Feuga, as the first Bishop of the newly formed Diocese of Mysore, comprising the districts of Mysore, Mandya, Kodagu, Shimoga, Hassan, Chikmagalur, the Nilgiris and a part of Coimbatore District. Diocese of Bangalore in the same year was bifurcated from the diocese of Mysore.
Fifteen years later, by His Apostolic Letter, “ Nuntiatur in Psalmis” dated 3rd July 1955, His Holiness Pope Pius XII erected the new Diocese of Ootacamund (Ooty) separating it from the Diocese of Mysore with the Nilgiris and a part of Coimbatore District in Tamilnadu. On the 16th November 1963, His Holiness Pope Paul VI, by His Apostolic Latter “Indicae Regionis Conditio”, created the new Diocese of Chikmagalur, bifurcating the districts of Chikmagalur, Hassan and Shimoga, from the existing Diocese of Mysore.
The present Diocese of Mysore comprises the four civil districts of Mysore, Mandya, Kodagu and Chamarajanagara. It is bordering clockwise on the Archdiocese of Bangalore, Ootacamund, Salem, Mananthavadi, Kannur, Calicut, Mangalore and Chikmagalur.
Statistics of the Diocese of Mysore
| Civil Districts | Chamaraja Nagar Kodagu Mandya Mysore |
| Deaneries | Chamaraja Nagar Hunsur Kodagu Kollegal Mandya Mysore |
| Languages Spoken | Kannada, Tamil, Konkani, Telugu, Malayalam, English |
| Area | 21,051 Sq. Kms |
| Total Population | 59,187,55 (2001 Census) |
| Catholic Population | 1,07,998 |
| Diocesan Priests | 130 |
| Parishes | 80 |
| Mission Station | 04 |
| Religious Congregations | 83 |
| Priests | 19 |
| Brothers | 04 |
| Sisters | 55 |
| Societies of Apostolic life of Diocesan Right | 04 |
| Secular Institute | 01 |