Briton Thorne, 66, had been in an induced coma in an intensive care unit since Monday after suffering respiratory failure, according to a GoFundMe page set up to help pay for his medical treatment.
He died at 1.55 a.m. Wednesday after doctors turned off his machines, said Thorne's carer Julie O'Neill, who had been posting regular updates on the fundraising page since mid-April.
"I was with him all the way to his end and reading out messages to him from people," wrote O'Neill.
"He passed away very peacefully and without pain listening to his children saying they love him. That gives me some comfort in this difficult time."
Thorne shot to fame during the 1980s snooker boom and was one of the most recognizable players in the sport, according to a statement from the World Snooker Tour (WST).
"His gregarious nature made him one of the snooker-loving public's favourite characters as the sport thrived," reads the statement.
Born in Leicester, Thorne was friends with former England international Gary Lineker.
"Deeply, deeply saddened to hear that my friend Willie Thorne has passed away," tweeted Lineker, who began his professional career at Leicester City. "One of life's great characters. A marvelous snooker player and a lovely man, who's potted his final black much too soon. RIP Willie."