The cause was congestive heart failure due to complications from a kidney transplant and Hepatitis C.
Her 1991 album Unforgettable... with Love spent five weeks at No. 1, sold 14 million copies and won six Grammy Awards. Using technical wizardry, she recorded the album's centerpiece, "Unforgettable," as a duet with her late father, jazz legend Nat King Cole.
Cole recently canceled several concert dates in December and an upcoming one in February due to a recurrence of Hepatitis C linked to her past struggles with substance abuse.
Cole, who was married three times, is survived by her son Robert Adam Yancy.