He earned a degree in economics from the Catholic University of Leuven in 1951 and subsequently worked at a Hainaut-Sambre steel plant from 1958 to 1975.
In 1975, he left the steel plant to become chief of staff for Minister of Economic Affairs André Oleffe [fr].
Under his leadership, he resisted the party's tendencies to join DéFI in forming coalitions, advocating for its independence.
Yves de Wasseige was well known for his work as an economist and political analyst, publishing an economic manual titled Comprendre l'économie politique, which was republished multiple times by Éditions Couleur livres [fr].
The book still serves as the basis of the entrance examination of the Faculty of Economics at the Catholic University of Leuven.