Mar George Alencherry was born on 19th April 1945 in the parish of Thuruthy in the archdiocese of Changanacherry. After his schooling he entered seminary and his priestly formation was in the archdiocesan minor seminary at Parel and St. Joseph Pontifical seminary Aluva. On 18 December 1972 he was ordianed priest by Mar Antony Padiyara.

He has a doctorate on Catechesis from the Institut Catholique de Paris. In 1986 Mar Alencherry was director of the Pastoral Orientation Centre (POC) at Palarivattam and deputy secretary of KCBC. He was a professor at St. Thomas Apostolic Seminary, Kottayam until 1997. From 1994 to 1996 he was the protosyncellus of the Archdiocese of Changanacherry.

On 11th November 1996 Mar George Alencherry was appointed as the first bishop of Thuckalay by Pope John Paul II and he was ordained bishop on 2nd February 1997 at Thuckalay by Mar Joseph Powathil. On 24th May 2011 he was elected Major Archbishop. He was the first head to be elected by the Syro Malabar Church Synod. He assumed the office of the Major Archbishop on 29th May 2011. He was appointed a Cardinal of the Catholic Church and the titular Archpriest of San Bernardo alle Terme in Rome on 18 February 2012 in Rome. On 24 April 2012 Cardinal Alencherry was made a member of the Congregation for the Doctrine of the Faith, and a member of the Congregation for the Oriental Churches.