London had been in ill health since suffering a stroke five years ago. She died in hospital in Los Angeles on Wednesday.
London was once married to Dragnet star Jack Webb and had been out of the limelight since playing nurse Dixie McCall in his 1970s TV medical drama series Emergency!
She co-starred with Bobby Troup in the show who later became her second husband.
London was born Julie Peck in Santa Clara, California. She moved to Los Angeles at the age of 14 with her parents' radio and vaudeville act and broke into films in the 1940s.
She appeared in more than 20 films in the 1940s and 1950s, including Task Force, The Fat Man and A Question of Adultery.
Her legendary singing talents were heard in the 1956 Jayne Mansfield film The Girl Can't Help It.
But London is probably best remembered for her 1955 hit single Cry Me a River. The record sold three million copies and remained in demand into the 1960s.
Top vocalist
London married actor and TV executive Webb in 1947 and they were together for five years. He died in 1982.
Her second husband, Bobby Troup - who died in 1999 - was the composer, jazz musician and actor who wrote classic song Route 66. They were married for 39 years.
Troup booked London for a nightclub engagement that was followed by her hit with Cry Me A River and 32 albums.
London was voted one of Billboard's top female vocalists in 1955, 1956, and 1957.
Her best known songs include Around Midnight, In The Middle Of A Kiss, In The Wee Small Hours Of The Morning and My Heart Belongs To Daddy.
London moved into TV in the 1960s, appearing in an episode of Big Valley before landing the role of the head nurse in Emergency!
She stayed with the show for its five-year run on NBC before retiring from show business.
London is survived by her daughter with Webb and three other children from her marriage to Troup.