Lanctôt began her acting career in 1972, winning an Etrog (now called a Genie) award for best female performance for her starring role in Gilles Carle's La vraie nature de Bernadette. Since then, she has appeared in a wide variety of film and television roles, such as Les Corps Célestes (again by Carle); Ted Kotcheff's award-winning The Apprenticeship of Duddy Kravitz, Blood Relatives (by Claude Chabrol) and Guy Fournier's Radio-Canada TV series, Jamais deux sans toi.