Tyler died "unexpectedly" in a hospital in Portugal where she was being treated for an illness, her family said Thursday in a statement on her website.
She was hospitalised in May in Faro, where she had a home, for emergency intestinal surgery and was later placed in an induced coma.
"Bonnie's family and team are heartbroken to announce that Bonnie unexpectedly passed away last night in hospital in Portugal as a result of the illness that she was being treated for, her family said on Thursday.
Tyler earned three Grammy nods, represented Britain at the Eurovision Song Contest 2013 - where she came in 19th - and was made a Member of the Order of the British Empire for her services to music by Queen Elizabeth II in 2023, all largely thanks to Total Eclipse of the Heart, which has had more than one billion streams, boosted by real eclipses in 2017 and 2024.
The song spent weeks at No.1, the video has surpassed one billion views and when Stereogum re-evaluated it in 2020, the music outlet declared it an "extinction-level event rendered in musical form."
"It's pop music as heart-pounding, chest-thumping, blood-gargling, heavens-falling passion explosion. It's sheer spectacle. It's fireworks and lasers and lightning and thunder. It soars and swoops and barrel-rolls," the site said.
The song has never really gone away, covered by the English singer Nicki French in 1995 and the band Westlife in 2006.
Cate Blanchett sang it while hitting Billy Bob Thornton with her car in 2001's Bandits, it appeared at a wedding scene in 2003's Old School and One Direction sang it in 2010 on a UK version of The X Factor.
Tyler has released many other hit songs over the years including Holding Out For A Hero, It's A Heartache and If You Were A Woman (And I Was A Man).
The star continued to make music and perform until her death, having released her 18th studio album The Best Is Yet To Come in 2021.
Tyler was due to perform at the Sunshine Festival in Worcester, England, in August, along with a number of European dates, and was also booked to perform in Cardiff, Wales, in December.
Tyler was born - as Gaynor Hopkins - a coalminer's daughter in public housing in Skewen, Wales.
In 1976 she had to have surgery to remove nodules on her throat, leaving her with that trademark vocal sound.
Tyler was married to property developer Robert Sullivan.
with AP and PA
