Forestier topped the Quebec charts in 1973 with a version of the folk song "La Prison de Londres", performed with guitarist Claude Lafrance, and pianist Jacques Perron.

With this song Forestier started to turn away from the hard rock of her early career to a repertoire largely inspired by Quebec folk music, and to a more personal style, which she continued through the 1970s.

In 1980 Forestier played Marie-Jeanne, the robot waitress in the Montreal production Luc Plamondon, Michel Berger rock opera Starmania.

Forestier defended Yann Martel's novel Histoire de Pi in the French version of Canada Reads, which was broadcast on Radio-Canada in 2004.

In March 2019, she was one of 11 singers from Quebec, alongside Ginette Reno, Diane Dufresne, Céline Dion, Isabelle Boulay, Luce Dufault, Laurence Jalbert, Catherine Major, Ariane Moffatt, Marie Denise Pelletier and Marie-Élaine Thibert, who participated in a supergroup recording of Renée Claude's 1971 single "Tu trouveras la paix" after Claude's diagnosis with Alzheimer's disease was announced.