Most Rev. Samuel Mar Irenios was born on 13 May 1952 hails from Kadammanitta in Pathanamthitta District of Kerala, India, in the Major Archieparchy of Trivandrum. His parents are late K. C. Thomas and Annamma. After his High School Education in Kadammanitta, he joined in the St. Aloysius Minor Seminary Trivandrum. On completing the bachelor’s degrees in Philosophy and Theology from St. Joseph’s Pontifical Seminary Aluva he was ordained priest on 22 December 1978 by Most Rev. Benedict Mar Gregorios. He completed secular degrees of BA, MA, MPhil and PhD from the University of Kerala. After being Appointed Lecturer in Mar Ivanios College, he later served as the Principal of St. John’s College Anchal and retired as the Principal of Mar Ivanios College Trivandrum. From 1979 he served several parishes such as Erathumpamon, Muttathukonam, Pampukala, Vattakarikkam, Kuttichal, Vengode, Manjakala, Kunnapuzha, Kalliyal, Thirumala, Chalai, Palayam, Thiruvallam, Karakulam, Kallayam, Chenckalchoola, Anchal, Thazhamel and Ozhukuparackal as parish priest. He served as the Syncellus of the Major Archieparchy of Trivandum. Languages known are Malayalam, English and Syriac.
He was appointed the Auxillary Bishop of the Major Archieparchy of Trivandrum on 25 January 2010. He was ordained Auxillary bishop on 13 March 2010. He took charge of the office as the Co-adjutor Bishop of the Eparchy of Pathanamthitta on 29 April 2018. On 8 June 2019 he was appointed the second Eparchial Bishop of the Eparchy of Pathanamthitta.