Her son, actor Corbin Bernsen, made the announcement on his Facebook page and on Twitter.
"My mother passed away this morning just a short time ago, peaceful with my sister by her side, in her sleep," Bernsen wrote.
Cooper’s character broke new ground by weaving storylines mirroring her own life in The Young and the Restless plotline. Katherine “Kay” Chancellor received a mid-1980s facelift, using footage from Cooper’s actual procedure and her character's battles with alcoholism were something Cooper went through as well.
The much-married Chancellor also crossed over to another daytime soap, The Bold and the Beautiful, for two episodes in 2005.
Cooper’s career began in the 1950s with a role in the Western The Redhead from Wyoming.
She then launched into a long string of roles on TV, including NBC’s Tales of Wells Fargo and CBS’ Dick Powell’s Zane Grey Theater and multiple appearances on Perry Mason, The Big Valley and Ironside.
She appeared in dramas such as The Adventures of Kit Carson, Cheyenne and Wagon Train.
More recently she made TV appearances in Gentle Ben, Touched By an Angel and L.A. Law, where she appeared beside Bernsen. She remained with The Young and the Restless from 1973 until this year, appearing in more than 1,000 episodes.
In 1962, Cooper earned her first primetime Emmy nomination for her performance in Ben Casey and a second came in 1987 for L.A. Law. She was nominated nine times for a daytime Emmy in the role of Katherine “Kay” Chancellor and won in 2008, as well as being honoured with a lifetime achievement Emmy in 2004.
Cooper was married to TV producer Harry Bernsen, Jr. for 23 years before divorcing. They had three children, all of whom are actors: Corbin Bernsen, Collin Bernsen and Caren Bernsen.