Bellemare taught at the University of Quebec at Montreal from 1972 to 1994 in the economics department and, from 1991 to 1994, in the business administration department. Her areas of specialization included macroeconomics, labour economics and public policy. She published several books and academic articles on the subjects of full employment, income security, pension and population aging. The last one, Créer et Partager la Prospérité, was published in 2013 by the Presses de l’Université du Québec.
Bellemare participated in the creation of the Forum pour l’emploi (1987–1996), a non-profit association of key decision-makers from employers, unions, communities and institutions whose goal was to promote employment.
She was appointed for two terms on the Economic Council of Canada (1983–1991), the National Statistics Council (Statistics Canada) (1990–1996) and the Institut de recherche et d’information sur la rémunération (IRIR) (1991–1994). She also participated weekly from 1988 to 1991 as an economics columnist on Télé-Québec’s public affairs program “Questions d’argent.”
In 1994, Bellemare was appointed President and Chief Executive Officer of the Société québécoise de développement de la main-d’œuvre (SQDM), whose mandate was to manage the entire range of federal and provincial labour force development programs. She was also Chair of its board of directors. When the SQDM was dissolved in 1997, Bellemare became Chair of the Commission des partenaires du marché du travail, where she served until 1999. She was part of the team who negotiated the labour market agreement between the Québec and the federal government.
Between 2000 and 2003, Bellemare worked as a consultant. During this time, she was responsible for the QFL Solidarity Fund’s employment periodical La minute de l’emploi. From the fall of 2003 to the spring of 2007, Bellemare worked at the Conseil du Patronat du Québec, first as Vice-President of Research and later as Senior Vice-President and Chief Economist. She subsequently became Special Economic Advisor to Quebec’s Official Opposition Leader, Mario Dumont, through the end of 2008. She was candidate for provincial elections for Action démocratique du Québec (ADQ), serving as the ADQ’s spokesperson for public finance and employment. Bellemare then joined CIRANO (the inter-university research institute) as an associate fellow.
She was appointed Senator in 2012 by Prime Minister Harper. She became an independent senator in March 2016, was the Legislative Deputy to the Government Representative (formerly Deputy Leader) from May 2016 to November 2019, then sat as a member of the Independent Senators Group and, at the beginning of the 44th Parliament, she joined the Progressive Group in the Senate.