Conley was born on July 18, 1934 in Dublin, Ireland and grew up in Chicago, Illinois. At the age of 15, she was discovered by legendary Broadway impresario Jed Harris who cast her as the Irish maid in a touring production of the 19th century melodrama The Heiress, which starred Basil Rathbone. After graduating high school, she toured the country with classical theater companies before appearing in Shakespearean roles on Broadway with the Helen Hayes Repertory Theater. She later appeared in a Broadway revival of the Night of the Iguana, with Richard Chamberlain, and in David Merrick's musical The Baker's Wife. Her Los Angeles theater credits included Cyrano de Bergerac and Night of the Iguana (both with Chamberlain), The Time of the Cuckoo with Jean Stapleton and Ring Around the Moon with Michael York.
Conley's first feature film was the Alfred Hitchcock suspense thriller, The Birds. It was Hitchcock himself that cast Conley in the movie. From there, Conley's portfolio of feature films blossomed. Over the next two decades, Conley appeared in such works as Faces, Minnie & Moscowitz, Valley of the Dolls, Play it as it Lays, Lady Sings the Blues, as well as Tough Guys, with Burt Lancaster and Kirk Douglas.
On television, Conley appeared in numerous made-for-television movies and guest starred in countless primetime series. The list of Conley's appearances include Robert Kennedy & His Times, The Fighter, The Choice, Return Engagement, and The President's Plane is Missing as well as The Cosby Show, Murder, She Wrote, Cagney & Lacey, Little House on the Prairie, The Mary Tyler Moore Show, and Highway to Heaven.
In 1979, Conley landed her first daytime role as Rose Deville on The Young and the Restless. Conley appeared on the CBS soap from 1979 to 1980 and then again from 1986 to 1987. Her Y&R role led to minor roles on NBC's Days of our Lives and ABC's General Hospital. In December 1988, Conley returned to the world of William Bell's soaps with the role of Sally Spectra on The Bold and the Beautiful.
The actress died on January 14, 2007 following a battle with stomach cancer. She was 72.