Kohona was the Secretary, Ministry of Foreign Affairs of Sri Lanka from 2006 to 2009. Ambassador Kohona was the Permanent Representative of Sri Lanka to the United Nations in New York from 2009 to 2015. During this period he was elected as the Chair of the UN GA Sixth Committee (Legal) in 2013.
Kohona headed the Ministry of Foreign Affairs of Sri Lanka from 2006 to 2009. He represented Sri Lanka at the United Nations in New York from 2009 to 2015 and was elected as chair of the UN GA Sixth Committee (Legal) in 2013.