Tremblay was affiliated with the Bloc Québécois. He was re-elected in the 1997 and 2000 elections. He represented the riding of Lac Saint-Jean in the Saguenay-Lac-Saint-Jean region.
Tremblay was re-elected to the MNA in the 2003 election.
He served as the opposition critic for environment until his resignation in 2006. In 1998, he removed his green upholstered chair from the Canadian House of Commons and returned with it to his Quebec riding in protest of the gaps between the rich and the poor.
He returned the chair a week later. In August 2004, Tremblay was injured when the small plane he was flying crashed near Alma, Quebec after hitting Hydro-Québec"s high-voltage power lines.