After his activities as an assistant to the UCL law school (1976-1981) and as an advisor to the SRIW (1981-1990), Karl-Heinz Lambertz was minister since 1990 and minister-president of the German-speaking community of Belgium from 1999 to 2014. Until September 2016, he was President of Parliament for the first time. Meanwhile, Mr. Lambertz represented the German-speaking community in the Belgian Senate before becoming Speaker of Parliament again in June 2019.
At European level, Karl-Heinz Lambertz has been a member of the Committee of the Regions (CoR) since 2001 and was its first Vice-President between February 2015 and July 2017. In July 2017, he was elected CoR President until February 2020. Currently, He is a member of the board of this European institution. He has also been a member of the Congress of Local and Regional Authorities of the Council of Europe since 2000 and its vice-president since October 2016. Since November 2020, he is again president of the Association of European Border Regions (ARFE), which he had already chaired from 2010 to 2017.