The  Catholicos His Holiness Baselios Geevarghese II took special interest to see that the services of Father Mathews are utilised in a still better way for the church and the community. On May 15, 1953 he was ordained as a Bishop of Orthodox church. He was only thirty eight years at that time.  

The young Bishop grew in stature very soon. As Metropolitan of the Diocese of Kollam he was fully responsible for its growth and progress and the number of parishes almost doubled within a short period. Several monasteries and convents were started. A large number of educational institutions and hospitals were established. His services in the field of education and social service are all very well known. Several Colleges, Schools, Hospitals and other service institutions are successfully established and administered under his direct control and leadership. He has travelled wide in various countries. America, Canada, Europe, Malaya, Singapore, Gulf countries etc. and has attended various international meetings and conferences. It was in 1980 that he was unanimously elected by the Malankara Syrian Christian Association as successor to the throne of Catholicos of the East and Malankara Metropolitan.

In recent years some of the new schemes started under his directions are found to be of much help and benefit for the community at large. A Civil Service Academy was started at Thiruvananthapuram, to give proper training for candidates appearing for I. A. S.; I. P. S.; I. F. S. and other Central Service Examinations. With a view to provide shelterforthe poor, an House Building Assistance project was started. The Community Marriage Scheme is found beneficial for the marriage of poor girls. Human Resources Development and Services Wing is also helpful for the community in general. As President of the Ecumenical committee in Kerala and also in various other Inter -Church Committees he has shown excellent leadership. He keeps in touch with Heads of other Churches constantly and is keenly interested to promote Ecumenism .