Her death was confirmed by her son, actor Corbin Bernsen, on his twitter account, reported TMZ online.
"Mom passed this morning. She was in peace and without fear. You all have been incredible in your love. In her name share it today with others," Bernsen posted.
Cooper had been suffering from an undisclosed illness. The cause of death was not given.
Cooper began her career in the 1950s and scored her big break in 1953 western 'The Redhead from Wyoming'. She went on to land roles in movies like 'The Man from the Alamo', 'House of Women', 'The Glory Guys' and 'Kansas City Bomber'.
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However, her biggest break came in 1973 when she was cast as Katherine Chancellor on the long-running US soap opera 'The Young and The Restless', a role she played right up until her death.
The Chancellor character earned her multiple Daytime Emmy nominations and she finally won the Outstanding Lead Actress in a Drama Series title in 2008. She was also awarded a Lifetime Achievement Emmy in 2004, 11 years after unveiling her own star on the Hollywood Walk of Fame.