The history of the Archdiocese dates back to the Apostolate of St. Thomas. Cranganore (Musiris) where he landed and Palayur where he established the first Church Community in Kerala belongs to this Archeparchy.
From the 4th century onwards St. Thomas Christians established relationship with the Church of Persia. The Bishops from the Church of Persia who came to nurture the Church in India had their residence at Kodungalloor, with the title of the “Metropolitan and Gate of all India”. The ‘Metropolitan’ changed his residence from Kodungalloor to Angamaly in the 16th century due to certain political reasons. After the death of Mar Abraham in 1597 St. Thomas Christians were subjected to the Latin Bishops from 1599 and continued to be so until 1887.
H.H. Pope Leo XIII of illustrious memory, by the epoch- making bull “Quod Jam Pridem” of May 20, 1887, separated the Syrian Catholics from the Latins. Syrian catholics who were under the Varapuzha Vicarite of Propaganda Jurisdiction and Kodungalloor Archdiocese of Padroado jurisdiction were placed under the newly erected Syrian Apostolic Vicariates of Trichur and Kottayam. The river Periyar (Aluva) was the dividing line of the two Vicariates: North of Periyar belonged to Trichur and South to Kottayam. Thus the Vicariate of Trichur had within its territory three of the most ancient Christian centres i.e, Kodungalloor- the cradle of Christianity in India, Palayoor and Angamaly. Mgr. Adolphus Edwin Medlycott was the first Vicar Apostolic of Trichur.
Nine Years later, by the Brief “Quae Rei Sacrae” of July 28, 1896 the same Holy Father reorganized the two Vicariates into three: Trichur, Ernakulam and Changanasserry with Indians of the Syro-Malabar rite as their Vicars Apostolic. Accordingly, Mar John Menacherry became the first native Vicar Apostolic of Trichur. The southern boundary of Trichur Vicariate was limited to the area bordered by the river Chalakudy.
The rapid and remarkable progress that the Syrian Catholics made under the Indian bishops in the course of a few years was highly appreciated by the Apostolic See and as a result, on December 21, 1923 by the bull “Romani Pontifices” of Pope Pius XI, the Syro-Malabar Hierarchy was established, raising Ernakulam to the status of a Metropolitan See with Trichur, Changanasserry and Kottayam its suffragan Eparchies. Mar Francis Vazhappilly became the first Bishop of the Eparchy of Trichur.
On March 11, 1944, H.E. Mar George Alapatt was nominated the Bishop of Trichur. On May 1, 1944 the consecration of Bishop Mar George Alapatt was held in Trichur. Pope Pius XII, by the bull “Saepe Fidelis” of April 29, 1955 extended the jurisdiction of the Eparchy of Trichur to the Civil district of Coimbatore. Later, on June 4, 1970 Mar Joseph Kundukulam was nominated the Bishop of Trichur and he was consecration on August 16, 1970. In the same decade the eparchy of Trichur ws bifurcated twice. On June 20, 1974, Pope Paul VI by the bull “Apostolico Requirente” divided the Eparchy of Trichur erecting the Eparchy of Palghat which consisted of the civil districts of Palakkad and Coimbatore. Again on June 22, 1978, Pope Paul VI separated the entire taluk of Kodungalloor, greater Part of Mukundapuram and small portions of Paravoor and Aluva to the north of the river Chalakudy from the Eparchy of Trichur and erected the Eparchy of Irinjalakuda by the Apostolic bull “Trichuriensis Eparchiae”
Pope John Paul II inaugurated the centenary celebrations of the Eparchy of Trichur on February 7, 1986 at St. Thomas Nagar, Trichur, in the presence of about one million faithful. On May 20, 1987 the centenary was celebrated. The concluding functions on August 9, 1987 were presided over by Simon Cardinal Lourdusamy, the then Prefect of the Congregation for the Eastern Churches. On May 12, 1987, as directed by S.M.B.C., the Eparchy of Trichur took up the pastoral care of the Syro-Malabar faithful of Bombay. Mgr. Paul Chittilappilly the then Vicar General of the Eparchy, lead the team of priests sent for the Mission. The Eparchial Renewal Project - EVX-2000, which lasted 10 years was inaugurated on December 30, 1990.
On January 18, 1994, Mother Theresa laid foundation stone for Divyahrudayashramam, Chennaipara and visited Ashanilayam, Peace Home, Santhivanam and Mercy Home at Peringandoor.
The long awaited expectation of the faithful of the Eparchy of Trichur was fulfilled on May 18, 1995 when the Pope John Paul II raised the Eparchy to the Metropolitan status, with Eparchies of Irinjalakuda and Palghat its suffragans and Bishop Mar Joseph Kundukulam its first Metropolitan Archbishop. On August 17, 1995, he was Installated as the First Archbishop of the Archeparchy of Trichur. Mar Jacob Thoomkuzhy, the new Archbishop was appointed on December 18, 1996. His Installation as the successor of Mar Joseph Kundukulam was held on February 15, 1997.
On December 8, 1997, the foundation stone for the Marymatha Major Seminary was blessed by H.G. Mar Jacob Thoomkuzhy and laid by H.G. Mar Joseph Kundukulam at Mulayam. On April 9, 2000 Beatification of Bl. Mariam Thresia, founderess of CHF was held at St. Peter’s Basilica, Rome by H.H. Pope John Paul II. Opening the opportunities for Professional Education, prestigious professional colleges like Jyothi Engineering College, Cheruthuruthy (September 12, 2002), Mahajubilee Training College (September 19, 2002), Mulloorkara, Jubilee Mission Medical College (August 24, 2003) were started.
The Archdiocese hosted 26th Biennial General Assembly of CBCI at Marymatha Major Seminary, Trichur from January 7, 2004. Mar Ignas Cardinal Mouza I Daoud, Prefect of the Congregation for the Eastern Churches, Archbishop Pedro Lopez Quintana, Apostolic Nuncio, Archbishop Folly, President of the Council for Social Communication, Rome, and so on were present on the occasion. The Beatification of Bl. Euphrassia CMC was held at Ollur on December 3, 2006.
The Archeparchy of Trichur was privileged for the first time to get an auxiliary bishop in the person of Mar Andrews Thazhath. He was nominated on March 18, 2004 and was ordained bishop on May 1, 2004. Mar Andrews Thazhath was installed the 3rd Archbishop of Trichur on March 18, 2007.
Causes of the Servants of God Fr. Augustine John Ukken and Fr. Antony Thachuparambil started on November 30, 2007 and on June 9, 2009 respectively.
Mar Raphael Thattil was appointed the Auxiliary Bishop of Trichur on January 18, 2010 and was ordained by Mar Andrews Thazhath on April 10, 2010. Ramanathapuram, a new suffragan eparchy was erected for the Tamil Nadu region bifurcating the eparchy of Palghat on 18th January 2010 and Mar Paul Alapatt from the Archdiocese of Trichur was nominated the First Bishop of the Diocese. First Curia Bishop of the Syro Malabar Church is also from this Archdiocese in the person of Mar Bosco Puthur hailing from parappur, the home parish of Mar Joseph Kundukulam. Archdioce of Trichur is honoured again when Mar Andrews Thazhath was elected the President of K.C.B.C. on 16th December 2010, he being the first from the Archdiocese to hold this prestigious position in the special scenario of Kerala. Silver jubilee of the visit of H. H. Pope John Paul II was celebrated with Jubilee Memoir rally and Viva il Papa Exhibition on 6th February 2011. Archbishop Salvatore Pennacchio, the Apostolic Nuncio to India and Nepal inaugurated the Post Centennial Silver Jubilee Celebrations on 22nd May 2011.
The present Archeparchy of Trichur has the following boundaries - North : Bharathapuzha in Malappuram district and Trichur - Palakkad district boundary; West : Arabian Sea; East : Trichur district boundary; South : Southern boundary of Valapad village and Karuvannur, Karanchira, Kurumali and Mupliam river.