Born Barbara Blakeley, the Bosworth, Missouri, native began her modeling career at 18 after her family moved to Long Beach, California.
The spokesman, in an official release from the Barbara Sinatra Children's Center, said she died of natural causes and was surrounded by friends and family at the time of her death. The couple were married for 22 years when the singer died of a heart attack in 1998.
It was her third marriage, Sinatra's fourth and the most enduring union for both.
"He was always very much a gentleman and he really cared about treating me well", Sinatra told the New York Times in 2011 about her famous husband.
Police chief in United States city quits after fatal shooting
Harrity told investigators from the Minnesota Bureau of Criminal Apprehension he had heard a loud sound near the patrol vehicle . "I mean, how can a woman out in the street in her pyjamas seeking assistance from the police be shot like that?" he said .
Socialite Barbara previously admitted she was unsure why Frank wanted to be with her instead of another star like his former spouses, Ava Gardner and Mia Farrow.
"But the best way she used Frank", he added with a chuckle, "was she would say, "I need a half-million dollars for this, so you do a concert and I get half the money". "You worry about new ones, '" Sinatra said.
The couple were married for nearly 22 years, the longest of all his marriages, during which time she set up the Barbara Sinatra Children's Center, to help abused children.
The center provides services for abused, neglected and at risk children.
Shortly after her move, she married Robert Oliver, but they divorced, and she then married Zeppo Marx in 1959. In March, KESQ reported that the Center had raised $250,000 in conjunction with Children's Hospital Los Angeles.