Acker was born in Toronto, Ontario, Canada. She began her professional acting career with a television appearance in a made-for-television movie of Anne of Green Gables. She joined the Stratford Theatre cast. She travelled with the troupe to England, and stayed to seek acting work. She made her film debut there in Lucky Jim (1957). Turning down a long-term contract with the producers of Lucky Jim, Acker returned to Canada in 1957 with her husband to raise a family. Acker returned to acting in Canadian television productions. She appeared in a 1961 Canadian Broadcasting Corporation (CBC) production of Macbeth with Sean Connery, directed by Paul Almond. During the 1960s, she also modelled, appearing in print advertisements. Her first American film appearance was in the cult John Boorman action film Point Blank (1967) starring Lee Marvin and John Vernon. From that point, Acker appeared in film and television roles in Canada and the United States. She made her last feature film appearance in 1981 and her last television appearance in 1992.