He has a Doctor of Philosophy.
In political science from the University of Paris X. Mitri served as a visiting professor in several international institutions. Mitri was environment and administrative development minister in 2005. He was minister of culture and foreign minister in the cabinet formed by Fouad Siniora in 2005.
He was appointed information minister to the cabinet led by then prime minister Fouad Siniora on 11 July 2008 and the following government of Saad Hariri in 2009.
On 12 September 2012, he was appointed by the United Nations Secretary-General Ban Ki-moon as his special representative and head of the United Nations Support Mission in Libya (UNSMIL). He was appointed director of the Issam Fares Institute for Public Policy and International Affairs at the American University of Beirut on 16 October 2014.
He also chairs the board of Sursock Museum in Beirut and that of the institute of Palestine Study. Mitri states his role is more as an advocate for the intellectuals and the artists along with their freedom of expression and thought.