Cadeau was born on January 10th, 1948 in Burlington, Ontario. Cadeau has performed in stage and television acting and is a strong supporter of the Stratford Festival since 1998. Cadeau is best known for her role as Janet King in the series Road to Avonlea. Cadeau is married and has three children. In 1986, Cadeau was nominated as Best Supporting Actress for Separate Vacations in 1986 for the Genie Awards. She has received the Dora Mavor Moore Award for her performance in Saturday, Sunday, Monday. Lally has a daughter and two sons with Robin Weatherstone, and lives in Toronto. She currently designs homes & gardens at Lally Cadeau Design.