Geevarghese was born in Vattasseril family, the fifth child of Joseph Vattasseril of Mallappally and Aleyamma, Kolathu Kalathil of Kurichy, on 31 October 1858. Among his siblings, Ouseph Punnoose was also a priest. Following his elementary education at C. M. S. Middle School in Mallappally he completed his high school education from C. M. S. High School, Kottayam. On 12 October 1876, while still a high school student, he was ordained as a sub-deacon by Patriarch of Antioch Ignatius Peter III at Puthuppally St. George Church.
He studied at the Orthodox Theological Seminary (Old Seminary or Pazhaya Seminary), Kottayam for four years. He acted as the secretary to Mar Gregorios Geevarghese of Parumala. Geevarghese soon became a great Syriac scholar under the careful tutelage of St. Gregorios, who taught him at Parumala Seminary. He also learned Theology and Syriac language from Metropolitan Paulose Mar Ivanios at Vettikkal Dayara. On 16 October 1879, the sub-deacon Geevarghese was ordained as a full deacon and on 18 January 1880 he was ordained to priesthood by St. Gregorios himself. For some time, Fr. Geevarghese oversaw the theological education at Parumala Seminary. As per the existing tradition, he had been ordained for Parumala Seminary. During the period 1881–1908 he was the manager of the Seminary. In 1895, Fr. Geevarghese accompanied St. Gregorios on his visit to the Holy Land.
By 1880, Rev. Fr. Geevarghese had become an authority in the Syriac language, Canons of the Church, Church History, Faith and Doctrine, the Church Fathers, Patristics and Theology. In recognition of his expertise in Syriac and theology he was designated as Malankara Malpaan (a Doctor and Teacher of the Church). In 1887, he was appointed the Syriac teacher at the Old Seminary. Malpan Fr. Geevarghese spent his spare time reading, studying, and thinking which translated to his many writings, such as the book Doctrines of the Church. He also used his scholarship to edit and publish the order of Church worship to be used by the laity as an aid for participation in worship. He wrote and published a book titled Syriac - Chapter I for students of the language. During this period, he also authored the book Doctrines of the Church which remains one of the most authoritative and popular works describing Orthodox dogma and ecclesiastical traditions with thorough Scriptural explanations. In 1903, he translated the Holy Service book from Syriac to the local language Malayalam and published it with the blessings of the Church authorities.
In 1896, by the decision of Managing Committee of the Church, he was appointed as Principal of M. D. Seminary School, Kottayam. He served as the Principal for eight years, while teaching at the Old Seminary at the same time. His colleagues at the Seminary include the eminent Syriac scholar Rev. Fr. Mathen Malpan of Konat.
The Malankara Association meeting which convened at Parumala Seminary on 2 December 1902 nominated Fr. Geevarghese and Kochuparampil Paulose Ramban to the office of Metropolitan Bishop. On 2 November 1903 (the first Feast day of St. Gregorios), Fr. Geevarghese Malpan was blessed as a Ramban (monk) at Parumala Seminary by Mar Dionysius V (Pulikkottil Joseph Mar Dionysius II). Following this, he moved to the Old Seminary. The Malankara Association meeting of 14 February 1908 officially elected him along with Kochuparampil Paulose Ramban for consecration as Metropolitan. In the same year, the Patriarch of Antioch Ignatius Abded Aloho II asked the two elected monks to reach Jerusalem during the Great Lent for the ordination. The two-week-long journey began on 13 April 1908. The party which also included Kallasseril Punnoose Ramban (later Catholicos Geevarghese II), Karottuveetil Fr. Yuyakkim (later Metropolitan Yuyakkim Mar Ivanios) and Dn. Mathews Paret (later Mathews Mar Ivanios) arrived at Jerusalem on 23 April (Holy Saturday). After some delay, the Patriarch Ignatius Abded Aloho II arrived from Turkey. On 31 May 1908, the ordination took place at Sehion House (where Jesus had the Last Supper). Fr. Geevarghese was enthroned as Geevarghese Mar Dionysius Metropolitan by the Patriarch. The ceremony was attended by representatives of Coptic and Greek Orthodox Churches. Mar Dionysius was appointed as the Bishop of the Malankara Church in general and as the assistant to the Malankara Metropolitan Mar Dionysius V The newly ordained bishop served as the Assistant Malankara Metropolitan for almost a year.
On 26 November 1908, the Malankara Association convened at the Old Seminary and elected Geevarghese Mar Dionysius as the successor to Malankara Metropolitan Mar Dionysius V. The next year he assumed full office of Malankara Metropolitan following the demise of Mar Dionysius V and served and led the Church in that capacity until his death in 1934 when he and the Church triumphed in establishing the official constitution of the Malankara Orthodox Church.
He was an outstanding orator who was well aware of the importance of the vitality and Christian persuasiveness of the Bible when delivering the speeches to the faithful. Prayers and fasting were the pillars of his spiritual foundation. In addition to the liturgical hours of prayer, he spent much time in private prayers and silent meditations behind closed doors. In spite of his busy schedule, he was also able to focus on three to four lessons from the Holy Bible everyday. Despite of the many spiritual qualities he shared leadership qualities like domineering charisma and progressive mindedness. The church recognizes him as a living saint of his time on earth.
Mar Dionysius VI and his fellow clergies have played a central role in elevating the primate of Malankara Orthodox Church to the title Catholicos of the East. By establishing the Catholicate in Malabar, the visionary Metropolitan succeeded in defending the sovereignty and independence of the St. Thomas Christians of India. Mar Dionysius VI also prepared a first draft of the Church Constitution with the aid of Patriarch Ignatius Abdul Masih II and of using his profound knowledge in the Canons of the Church. This draft was used to prepare the Church Constitution of 1934. In his last encyclical, he wrote to the entire Malankara Church:
Being a great guide and example of Christian monasticism, the legacy of Mar Dionysius survived through his successors as well as students including Catholicos of the East H. H. Baselios Geevarghese II and the saintly Metropolitan Kuriakose Mar Gregorios of Pampady. It is said that the metropolitan was inspired by the reformation movements that has happened during his time, but always kept an ardent position in his upbringings in faith, like Mary of Bethany(Luke 10:42) he took from it what was good for his people and administration.
Mar Dionysius VI experienced physical suffering on 13 February 1934, and suffered from paralysis on 16 February. Still, the Metropolitan had clear memory. On 21 February, H. H. Baselios Geevarghese II administered him the service of Anointing. Two days later, Mar Dionysius VI died on 23 February 1934, and was buried the next day in the Chapel of Old Seminary, Kottayam, near the tombs of his predecessors.
In his speech that day, H. H. Baselios Geevarghese II said:
Items used by Vattasseril Thirumeni are kept in Old Seminary Kottayam and Mar Elia Chapel Devagiri, Kangazha, Kottayam, Kerala.
Mar Dionysius VI was exalted as a saint and confessor to the faithful. On the 69th feast day of Mar Dionysius VI (24 February 2003), he was canonized by the Episcopal Synod of Malankara Orthodox Church headed by H. H. Baselios MarThoma Mathews II, Catholicos of the East. St. Dionysius is the second Indian Saint to be canonized by the Malankara Orthodox Syrian Church. The Catholicos Baselios Geevarghese II might have foreseen this when he instructed the sentence "The time will not dim his glory" to be engraved on the tomb of Mar Dionysius VI. 23 February is observed as the saint's feast day.
Honoring the Saint's memory, several churches and educational institutions have been established including St. Dionysius Church in Al Ain, U.A.E., st dionysius orthodox church desertland, dammam(under diocese of thrissur), St. Dionysius Indian Orthodox Church, Auckland, New Zealand, St. Dionysius Orthodox Church, Dasarahalli, Bangalore, St. Dionysius Church, Aravali (Gurgaon) and Mar Dionysius Senior Secondary School in Mallappally, Kerala, to name a few. M. G. D. Ashram (monastery) at Panayampala, Kerala was founded in 1980 with St. Dionysius as its Patron Saint. The Ashram has an orphanage (balabhavan) in its care since 2000. The first church in the name of St. Dionysius was consecrated in Trivandrum by HG MathewsEphiphanios in February 2004.