She died "unexpectedly" in hospital in Portugal where she was being treated for an illness, her family said in a statement on Thursday.
"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," it said.
"We will issue a further statement shortly but for now ask for privacy to deal with this tragedy."
Tyler was placed into an induced coma in May, but a few weeks ago, it was revealed she had woken up, though she remained "seriously ill".
"Although her condition is improving, the recovery process is slow," a representative said.
At the time, it was reported she was expected to make a full recovery.
The gravelly voiced singer, whose real name was Gaynor Hopkins, was discovered by a talent scout at a club in Swansea, Wales, and released her first single, Lost in France, in 1977.
Her first major hit was It's A Heartache, released the same year and going to number four on the UK singles chart and three on the US Billboard Hot 100.
Her biggest hit was Total Eclipse of the Heart, which topped the chart on both sides of the Atlantic as well as in Australia and New Zealand in 1983, and earned her a Grammy nomination.
Holding Out for a Hero, another dramatic rock ballad, was released soon after.
In 2025, she teamed up with producers David Guetta and Hypaton for a club version of Total Eclipse of the Heart called Together, and earlier in 2026, the original version passed a billion streams on Spotify.
"I'm really happy, when you think about it, there's only 8.3 billion people in the world," she said at the time.
The Here She Comes hit maker represented the UK at the Eurovision Song Contest in 2013, coming in 19th place, and received an MBE for services to music in 2023.
Tyler is survived by her husband of more than 50 years, Robert Sullivan.
with AP and PA
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