The Malankara Orthodox Syrian Church was established in Kerala by St. Thomas, the Apostle of Jesus Christ in AD 52. The members of this Orthodox Syrian Church remained by and large in Kerala for centuries except for a few who ventured out to various parts of the country and even abroad. However, from the middle of the 19th century to the middle of the 20th century (1850-1950) greater numbers migrated out of Kerala looking for avenues of livelihood. Bangalore, being a city of opportunities and situated not too far from Kerala was a favoured destination. Not much is known of what these migrants did for their Orthodox worship during those early years in Bangalore. The earliest available record of their attempts at meeting as a congregation for worship is during 1937-39, when many Malayali Christians of various denominations got together at the United Theological College Chapel. Services which were exclusively Orthodox began in 1943. It is a landmark year for all the Orthodox Christians of Bangalore. They are indebted to Rev.Fr. M. P. Mathews, Modisseril for starting the Orthodox worship Services that year. He conducted Services at the St. Paul's Church, Shivajinagar once a month till the end of 1944.
After Rev. Fr. Mathews left, the Services became irregular. Worship services were conducted by priests who came to Bangalore from other places. They conducted services at the St. Mark's Cathedral. One such itinerant priest was Rev. Fr. T. G. Koshy who used to travel from Madras. He conducted Holy Qurbana at the Holy Trinity Church on 12th October 1947 and that marked the beginning of a long association of the Orthodox Christians with the Holy Trinity Church. The Church which formerly belonged to the British, at that time was under the control of the Indian Government. The Government transferred the church to the Church of South India in 1948. Nevertheless, the Orthodox Services at the Holy Trinity Church continued, albeit, intermittently till about mid 1950. The CSI congregation conducted their services early morning on Sundays and the Orthodox members had their worship later in the morning. The intense desire of the people of the Orthodox community for a regular worship and the services of a permanent vicar was fulfilled when Rev. Fr. V. C. Samuel was appointed as the first vicar by a Kalpana dated 18, May 1950 from H.G. Alexios Mar Theodosios the then Metropolitan of Quilon and in-charge of churches outside Kerala. The Orthodox community owes a lot to Rev. Fr. V. C. Samuel. The basic structure of our Parish as we see today was initiated by Rev. Fr. Samuel. He divided the parish into Wards, started Prayer Meetings, Bible classes, augmented the worship with a Choir and improved the finances through the collection of subscription. After ensuring the formation of an organized Parish, Rev. Fr. V. C. Samuel left to the USA for higher studies in April 1953. Then came a period of consolidation and the Orthodox Community grew from strength to strength led by Priests and leaders of true faith, dedication and vision. In 1954, Sunday School classes were initiated in the Church under the guidance of Rev. Fr. Geevarghese Thykadavil. In the same year the Kunnamkulam Group (later named City Ward) with the encouragement of Rev. Fr. Thykadavil began engaging regular Sunday School classes at the residences of their members and later at the United Mission School. The City Ward Sunday School merged with the mainstream Sunday School of the Church in the year 1981. Regular Services under a succession of dedicated Priests continued at the Holy Trinity Church.
In June 1964, the Patriarch of Antioch, H. H. Ignatius Yacoob III and in December 1964, the Catholicos of the East, H. H. Moran Mar Baselios Augen I visited Bangalore and blessed the Orthodox community which by now had become a sizeable population. With the burgeoning numbers, came the realization that more Churches had to be built. The members who lived in the vicinity of Jalahalli built their own Church in December 1966. In the year 1968 the dynamic Vicar of the Church Rev. P. V. Abraham and a very active Committee bought the piece of land at Richmond Town, Hosur Road where our Cathedral is presently located and started the building work. During the tenure of the next Vicar, Rev. P. M. Thomas the Church building was completed. The Church was consecrated by H.G. Mathews Mar Athanasios, the then Catholicos Elect and later the Catholicos H.H. Baselios Mar Thoma Mathews I. The Church was named after St. Gregorios Orthodox Church and the consecration was on 6th August 1972, the day of the Feast of Transfiguration. Majority of the members who worshipped at the Holy Trinity church, now moved to their 'own' church at Richmond Town, Hosur Road. The existence of the two Churches in the Parish necessitated the presence of a Vicar and an Assistant vicar. This arrangement continued till 1st January 1979 when the members worshipping at the Holy Trinity Church were declared to belong to the independent Parish - St. George's Parish by a Kalpana from the Diocesan Metropolitan H.G. Zachariah Mar Dionysius.
In the year 1993 the Golden Jubilee of the Church was celebrated under the leadership of the Vicar Rev.Fr. Abraham Marett. On 15th May 1994 the Jubilee celebrations culminated in a grand Get-Together and Public Function adorned by The Catholicos H.H. Baselios Mar Thoma Mathews II, H.G. Zachariah Mar Dionysius, the Diocesan Metropolitan, H.G. Alphonse Mathias, the Archbishop of Bangalore, Dr. P C Alexander, the Governor of Maharashtra, Shri. Veerappa Moily, the Chief Minister of Karnataka and Shri. Oommen Chandy, Finance Minister of Kerala. During the Function a Commemorative Volume titled – '50 Golden Years' was released. On 18th October 1994 the Church was elevated as Cathedral by a Kalpana from the Catholicos H.H. Baselios Mar Thoma Mathews II.
Looking back over the years the Cathedral can gratefully count its abundant blessings. It took the first baby steps under the Bahya Kerala Bhadrasanam and from 1976 grew under the Madras Diocese shepherded by the H.G. Zachariah Mar Dionysius and H.G. Yacoob Mar Iraneos.
On 27th January, 2007 The Catholicos H.H Baselios Mar Thoma Didymos I visited the Parish. There was a Public Reception in honour of His Holiness. Justice Cyriac Joseph spoke on the occasion and Dr. T. K Alex, a renowned Scientist from ISRO and a former member of the Parish was felicitated by the Holy Father on being bestowed the Padmashree. On 1st April 2009 the Bangalore Diocese came into existence. H. G. Abraham Mar Epiphanios, the Metropolitan of Sultan Batheri was in charge of the newly formed Bangalore Diocese for little over a year. On 15th August 2010, H.G. Abraham Mar Seraphim took over as the Metropolitan of the Bangalore Diocese. The Cathedral was blessed by the visit of the Catholicos H.H. Baselios Mar Thoma Paulose II on 27th March 2011. On that day His Holiness celebrated the Holy Qurbana and also conducted the Sunthroniso (Enthronement) of H.G. Abraham Mar Seraphim as the Metropolitan of Bangalore Diocese. With Bangalore becoming a Diocese and with a Metropolitan based here and available for guidance the Cathedral hopes to develop into an exemplary institution of Worship, Mission and Charity. Over the years the 'Mother church'- St. Gregorios Orthodox Cathedral being located in the heart of the City has fast expanded into a big vibrant worshipping community. Space constraints in the Church and the spread of the members in the far off suburbs in the city led to the creation of new Parishes. So far, the Cathedral has facilitated the formation of 7 new parishes in the city of Bangalore. The Cathedral also takes pride in the fact that it has not lost its Missionary focus. It has a vibrant Sunday School, an enthusiastic Youth League and an active Women's Wing – The St. Mary's League doing philanthropic work. It runs an English medium school, builds houses for the poor and helps the needy through its Benevolent Fund. Yet it is acutely aware that it needs to do much more work of Mission and charity. It is the Grace of our God Almighty, the intercession of the saints, the prayers, guidance, love and sacrifice of the Bishops, Priests and lay leaders and the worshipping community that has made the Cathedral what it is today.
The milestones achieved during the past 75 years is cherished by the Orthodox Community in Bangalore. To mark the occasion, we have comprehensive plan to celebrate the year 2018 as the 'PLATINUM JUBILEE ' Year. Apart from naming the building complex under construction as 'PLATINUM JUBILEE BUILDING', the church General Body has approved constructing a house for an eligible member during the Platinum Jubilee year.