Bert first held office as a councilman in the City of Brussels in 1987, and in 1991, became a member of the provincial council of Flemish Brabant.

Following the 1998 White Marches provoked by the publication of official reports on the Affaire Dutroux, Anciaux founded the think-tank, later political group, iD21 [nl], which aimed to confront the corruption and incompetence which the Dutroux affair had brought to light.

With the collapse of the Volksunie in 2001, split between left and right factions led by Anciaux and Geert Bourgeois which became Spirit and New-Flemish Alliance (NV-A) respectively.

In July 2004, he resigned this post and returned to his present position as Minister for Culture, Youth and Sport in Flanders.

In 2010, he was elected to the Belgian Senate and took over the position of faction leader of Vooruit in 2012, when Marleen Temmerman resigned from politics.