Fr. Thomas Vattathara, Salesain Provincial of Guwahati, and the national president of the Catholic Religious of India (CRI) described Fr Karotemprel a legend of our times, a loyal and committed Salesian, an erudite professor, an institution builder, and an active collaborator in the major missionary works in Northeast India

Fr Karotemprel served as President of the Sacred Heeart Theological College, Shillong, and Professor of Missiology at the Urban University, Rome. Spannning some four decades of academic career, he taught in several theological faculties in India and abroad. He also wrote extensively on theology, missionology and tribal cultures.

He is the founder of the mission review, Mission Today, formerly Indian Missiological Review in 1978, and the founder of Don Bosco Centre for Indigenous Culture, a treasure-house and a museum on north-eastern peoples and cultures. He established the Vendrame Institute Publications, and built a monumental library named after the pioneer Salvatorian missionary Fr Otto Hofenmuller. He was closely associated with some of the major projects like the Don Bosco Institute and  the Assam Don Bosco University. 

Fr. Karotemprel was one of the 30 theologians in the International Theological Commission established by  Pope John Paul II, headed by the then Cardinal Joseph Ratzinger (later Pope Benedict XVI). Oxford Encyclopedia of South Asian Christianity' (Oxford University Press, 2011) describes him as:'An internationally known theologian, based at Sacred Heart Theological College (SHTC), Shillong.

Father Sebastian’s younger brother is Bishop Gregory Karotemprel CMI, bishop Emeritus of Rajkot, and his only sister is Adoration Sister Maria Karotemprel, Provincial of SBAS, Ujjain Province.