Specialized in internal medicine and nephrology, she initially worked at the Cliniques Universitaires Saint-Luc in Brussels and later at the St. Elizabeth Maternity and Clinic in Namur.
[3][4] As an elected member of Parliament since June 2003, she has been an active participant in the Committee on Public Health, Environment, and Renewal of Society.
[6] During the federal elections of 10 June 2007, Catherine Fonck's list of the CdH in the House for the Province of Hainaut received 25,685 votes.
[7] She was elected member of Parliament but relinquished her seat to her substitute deputy to continue serving as the Minister for Children, Youth Assistance and Health in French Community.
She assumed the role of Secretary of State for Minister of Energy on 22 July 2014, succeeding Melchior Wathelet, until 13 October 2014.