[1] Celac started working as a junior clerk at the Ministry of Foreign Affairs of Romania immediately after graduation from the university.

[3] Throughout his career at the Ministry of Foreign Affairs, he was an expert and member of the Romanian delegation to 14 sessions of the UN General Assembly and Disarmament Committee in Geneva.

After removal from foreign service, he worked at the Encyclopedic Publishing House in Bucharest until the overthrow of the Ceaușescu regime on December 22, 1989.

In 1996, he was appointed Ambassador at large leading special envoy missions to the Balkans, Central Asia, Caucasus and the Middle East.

In August 2000, Celac resigned from the Ministry of Foreign Affairs to pursue academic and business interests and work as political analyst and environmental consultant.