Members of various religious orders, looked after the spiritual needs of the European communities in their trading centres along the coastal areas, including Cuddalore and Porto Novo.

While the Capuchins were looking after the Europeans in Pondicherry, the French Jesuits organized the Carnatic Mission for the Indian people.

Although the Bishop of these new missionaries had all the power of jurisdiction, he was not given the title "Vicar Apostolic", but instead called the "Superior of the Mission of the Coromandel Coast".

Rome successively gave him the jurisdiction over the Madurai, Coimbatore and Mysore areas, affected by the suppression of the Society of Jesus.

In 1928, a great part of the present diocese of Vellore was separated from Pondicherry and attached to the archdiocese of Madras and Mylapore.

Originally, the archdiocese included the former French settlements of Pondicherry, Karaikal, Chandannagar, Mahe, and Yanam.