The Holy Episcopal synod held at Devalokam Aramana nominated him as the successor to the Catholicos of the East & Malankara Metropolitan on 16 September 2021.

He was enthroned as Catholicos of the Apostolic Throne of Saint Thomas on 15 October 2021 by the Holy Synod of Malankara Church.

The chief celebrant of the enthronement service and Holy Eucharist was Kuriakose Mar Clemis who is the senior metropolitan of Malankara Orthodox Syrian Church.

[8][9][10] Cardinal Mar George Alenchery inaugurated a meeting held to congratulate the new head of the church.

Fr Alexander Kurien also conveyed wishes from the US President Joe Biden and presented a memento from the White House.

[16] This collection of essays on Christology was published in 2017 by the colleagues and students of Mar Severios at the Seminary to mark the 25th year of his Episcopal consecration.