[1] She became a founding member of Projet Montréal in 2004 while writing her master's thesis on urban sustainable development.
The returns office initially declared her elected by twelve votes, but the final recount showed that she was defeated by nine.
After the campaign, she became a leading Projet Montréal spokesperson and press attaché to its leader, Richard Bergeron.
Applebaum announced his executive committee on November 22, 2012, appointing Thuillier to one of two vice-chair positions, with responsibility for social and community development, family, seniors, youth and the status of women.
In the 2017 municipal election, Thuillier ran to replace Pierre Gagnier of Équipe Coderre, who was not seeking re-election.