After obtaining an Bachelor of arts degree from the Séminaire Sainte-Thérèse, Louise Harel undertook studies in sociology at the Université de Montréal. She holds a degree in law and has been a Member of the Bar since 1978. On seven consecutive occasions between 1981 and 2008, she was elected as an MNA for the Parti québécois to the National Assembly, for the riding of Hochelaga-Maisonneuve.
Over 28 years, she held numerous parliamentary and ministerial functions, such as Chair of the Education Commission, the Transportation and Environment Commission, Minister of Cultural Communities and Immigration, Minister of Employment, Minister of Income Security and Professional Training, Minister of the status of Women, Seniors and Housing, Minister of State for Employment and Solidarity, Member of the Priorities Committee, Minister of State for Municipal Affairs and President of the National Assembly. In 2002, she chaired the Organisation des parlementaires de la francophone. In 2004, she received the Grand Cross of the Order of La Pléiade. She became the official leader of the opposition in the National Assembly in 2005.