From 1968 till 1975 De Coninck was a teacher of history in Congo.
He started a career in Belgian diplomacy in 1975 and has been assigned from 1976 till 2000 to diplomatic posts in Barcelona, Nairobi, Islamabad, Rome (the Vatican), Dakar, The Hague, and both Kigali and Kinshasa as ambassador.
His last duty before he became Marshal of the Royal Household was at the Central Administration of the Belgian Foreign Ministry, where he was appointed special envoy for the Great Lakes (Central Africa).
He was president of Caritas International Belgium and Cercle Royal Africain et de l’Outre Mer.
[1] De Coninck died in Woluwe-Saint-Lambert on 11 March 2022, at the age of 77.