The 82-year-old leader succeeded Murlidhar Chandrakant Bhandare, whose tenure had ended on August 20 last year but had been continuing in office till Jamir's appointment.
Considered as an architect of modern Nagaland, Jamir had also served as governor of Maharashtra and Goa, besides being Chief Minister of the north-eastern state five times.
Jamir was first nominated a member of Lok Sabha in 1961 and appointed parliamentary secretary to then Prime Minister Jawaharlal Nehru, who was also in-charge of external affairs.
He was later elevated as deputy minister of railways and also served in other ministries at the Centre - labour and rehabilitation, community development and cooperation and food and agriculture.
A host of dignitaries, including chief minister Naveen Patnaik, attended the swearing-in ceremony.