The announcement was made by Nancy Sinatra Jr who wrote on her website that her mother had died at 6:02pm on Friday but did not say where.
"She fought hard to remain on this earth but time got the better of her," she wrote, adding that her mother passed 'peacefully.'
Peshawar-based singer brings Junaid Jamshed’s music back to life
"Godspeed, Momma and thank you for everything."
Frank and Nancy Sinatra had three children together.
Born Nancy Barbato on March 25 1917 in Jersey City, she met her future husband in the summer of 1934, while they were holidaying with their families on the Jersey Shore.
At the time, she was 17 and he was 19.
"Nancy was giving herself a manicure on the front porch when Frank came over with his ukulele and began to serenade her," according to an account on Sinatra's website.
"One thing led to another, and they started going together."
They wed in 1939 at the Our Lady of the Sorrows church in Jersey, then moved into a modest New York apartment while Nancy worked as a secretary.
The unheard plight of Pakistani playback singers
In 1950, humiliated by reports in the press of Frank's affair with screen siren Ava Gardner, Nancy filed for separation and their divorce was finalised in 1951.
Notorious for his romantic conquests, Frank would go on to marry Gardner (1951-57), then Mia Farrow (1966-68), and eventually model Barbara Marx in 1976.
But he remained close with Nancy until his death in 1998, according to the New York Times.
The oldest of their three children is Nancy Sinatra Jr, who went on to have a successful singing career with hits such as "These Boots Are Made for Walkin" and "Something Stupid", a duet she sang with her father.
Their second child Frank Jr, who died in 2016, also had a career in music, while the youngest is Tina Sinatra.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ