The history of the Diocese of Kalyan is very much intertwined with the history of the Syro - Malabar Church itself in India. Having its roots in the Apostolic Ministry of St. Thomas the Apostle himself who established seven communities of the Christian Church in Kerala in the first century itself. These Christians migrated to different parts of India. They concentrated mainly in the big cities of India. In Bombay, Pune and Nasik regions, they are found in large numbers. The spiritual care of these regions are assisted by lay association like Kerala Catholic Association (Bombay). St. Thomas Christians of India (Pune), etc.

On September 8, 1978 Pope John Paul II appointed His Eminence Antony Cardinal Padiyara, the then Archbishop of Changanacherry as the Apostolic Visitor to study the situation. The visit of Pope John Paul II to India in 1986 gave him a first hand experience of the living faith of the Syro - Malabar Christians of India. A Pontifical Commission was appointed and on the basis of its report came the all-important letter of the Pope to the Bishops of India observing that the present situation in Bombay - Pune region is mature for the Churches to take necessary steps in this regard. Finally on May 19, 1988 His Holiness Pope John Paul II made the announcement of the establishment of a new diocese for the Syro - Malabar Christians of Bombay - Pune - Nasik regions, the Diocese of Kalyan, and the designation of Mgr. Paul Chittilapilly as its first Bishop. The Bull, however, was signed by the Pope as on April 30, 1988. Thus the birth of the diocese and the appointment of the first Bishop took effect from April 30,1988. The Episcopal Ordination and the official inauguration of the diocese took place on August 24, 1988 at the Don Bosco Grounds, Matunga, Bombay.

After nine years of dedicated and pioneering work in the newly born diocese, Bishop Paul Chittilappilly was transferred to the diocese of Thamarassery in Kerala on December 18, 1996 and took charge on February 13, 1997. His successor and the second bishop of Kalyan Diocese was Mar Thomas Elavanal, whose consecration was on February 8, 1997 at Kannamwar Nagar, Vikhroli, Mumbai.