The Diocese of Tirunelveli is one among the 24 dioceses of the Church of South India (CSI). It is based at Tirunelveli, in the state of Tamil Nadu, southern India.

In 2014, the diocese had 718 churches, 99 pastors, and a membership of 1,34,277;^[1] it also ran 342 schools and fifteen colleges and hospitals. Holy Trinity Cathedral, at Palayamkottai is the Cathedral of Tirunelveli Diocese. The churches were established by the Church Missionary Society (CMS) missionaries and the Society for Propagating the Gospel (SPG) missionaries. In the year of 1919 Tinnevely Diocese Trust Association (TDTA) was formed by uniting both mission and also with Baptists and Presbyterians churches in the neighbourhood.

In October 1896, Tinnevelly (the British name for Tirunelveli^[2]) was separated from the Diocese of Madras and Rev. Samuel Morley was ordained as the first Bishop of the newly formed diocese.^[3][4]

V. S. Azariah, the first Indian bishop, came from Tirunelveli Diocese.

In November 2015, the Tirunelveli diocese increased the annual membership amount (in Tamil: Kanikkai) from Rs 100 to Rs 500. The retirement age of the pastors also increased by the CSI synod from 65 to 67, and a correction was made in the rule to permit pastors to remove someone from the diocese. Against all these decisions, members raised their voices. They requested to take a vote to implement these changes, but the Bishop ignored them and said that these changes are acceptable without proper voting. The members have thrown chairs to display their opposition. Due to the decision to increase the retirement age, J J Christdoss's retirement age also increased.^[5][6][7][8]

In 2014, one school teacher committed suicide as she was transferred. The diocese management was blamed for this.^[9]

In 2008, the then administration led by a bus company owner rigged the election and but were eventually defeated in the election.^[10]

• Samuel Morley (1896–1903)
• Arthur Williams (1905–1914)
• Edward Waller (1915–1923)
• Norman Tubbs (1923–1928)
• Frederick Western (1923–1928)
• Stephen Neill (1939–1944)
• George Selwyn (1945–1952)
• Augustine Jebaraj (1953–1970)
• Thomas Garrett (1971–1974)
• Daniel Abraham (1975–1984)
• Jason Dharmaraj (1985–1999)
• Jeyapaul David (1999–2009)
• JJ Christdoss (2009-2020)
• ARGST Barnabas 2021 -

• Primary and Middle Schools -323
• Higher Secondary Schools-13
• Colleges -6
• Teacher Training Institutes -3

• Church of South India
• Thoothukudi-Nazareth Diocese
• Madurai-Ramnad Diocese
• Diocese of Madras
• Trichy-Tanjore Diocese
• Diocese of Coimbatore
• Diocese of Kanyakumari
• Christianity in Tamil Nadu
• Church of North India
• Christianity in India