- American actress Rose McGowan became the fourth woman to accuse the 65-year-old of raping her.
- Weinstein's films have received more than 300 Oscar nominations and 81 statuettes.
The Academy of Motion Picture Arts and Sciences expelled Harvey Weinstein on Saturday, vowing that the era of "shameful complicity in sexually predatory behaviour" in the movie industry was over.
An emergency meeting of its 54-member board of governors, which includes stars such as Tom Hanks, Whoopi Goldberg and Laura Dern, voted "well in excess of the required two-thirds majority", it said in a statement.
"We do so not simply to separate ourselves from someone who does not merit the respect of his colleagues but also to send a message that the era of wilful ignorance and shameful complicity in sexually predatory behaviour and workplace harassment in our industry is over," the statement read.
An avalanche of sexual harassment, assault and rape accusations against Weinstein have surfaced since the publication last week of an explosive New York Times report alleging a history of abusive behaviour by the Hollywood mogul dating back decades.
As Weinstein's expulsion was announced, the London-based Sunday Times reported on a fifth alleged rape victim, British actress Lysette Anthony, who was said to have reported the 65-year-old to the Metropolitan Police last week.
Anthony, 54, who appeared in Woody Allen's 1992 film Husbands and Wives, told The Times that Weinstein attacked her in the 1980s.
On Thursday, American actress Rose McGowan became the fourth woman to accuse the 65-year-old of raping her.
"What's at issue here is a deeply troubling problem that has no place in our society," the Academy, which organises the Oscars, said.
"The board continues to work to establish ethical standards of conduct that all Academy members will be expected to exemplify."
Since the outbreak of the scandal, more than two dozen actresses including Mira Sorvino, Rosanna Arquette, Gwyneth Paltrow, Angelina Jolie and Lea Seydoux have come forward saying they were sexually harassed by the producer.
Some of the most recent allegations involved the former Bond Girl Eva Green, whose mother told French radio Weinstein had harassed her daughter for months, and British actress Alice Evans, who penned an essay for The Telegraph claiming she had rejected his advances, and believes it may have harmed her career.
Weinstein has not been seen in public since paparazzi descended upon him as he left his daughter's home in Los Angeles on Wednesday.
"Guys, I'm not doing OK but I'm trying," he said in a video obtained by ABC.
"I got to get help. You know what, we all make mistakes."
Celebrity gossip portal TMZ reported that Weinstein later flew to rehab in Arizona, possibly at The Meadows, a facility near Phoenix where golfer Tiger Woods and supermodel Kate Moss have been treated.
Weinstein's brother and business partner Bob told The Hollywood Reporter in an emotional interview published Saturday that he knew the tycoon was a cheater, but said he was unaware the extent of his "sick and depraved" behaviour.
"For me, I thought he was literally just going out there cheating in a pervasive way," he is quoted as saying.
"It wasn't like he even had a mistress. It was one after another and that I was aware of.
"But as far as being in a room and hearing the description in The New York Times? No way."
Weinstein appears to have garnered little sympathy from the public, either, according to a survey conducted by celebrity branding expert and bestselling author Jeetendr Sehdev.
Some 82 per cent of 2,000 people questioned as part of an ongoing study into American attitudes to celebrity and entertainment said he should be kicked out of the Academy.
Hollywood, too, has largely turned its back on Weinstein, with veteran filmmaker Oliver Stone and fashion designer Donna Karan offering the only words of support.
While Stone merely warned against Weinstein being "condemned by a vigilante system", Karan went further, triggering outrage when she suggested women had been seeking a reaction from Weinstein by dressing provocatively.
Expulsion is a sanction the Academy had used just once before Weinstein, according to The Hollywood Reporter, against "The Godfather II" actor Carmine Caridi.
He was accused of giving tapes of around 60 Oscar movies seeking consideration for the Academy Awards to a neighbour who turned out to be a pirate.
The LA Times newspaper reported that some members of the board had wrestled with the Weinstein vote, worried that it might set a precedent requiring governors to police members' behaviour.
Other A-listers including Bill Cosby, Roman Polanski and Mel Gibson have all been investigated for their treatment of women but have escaped expulsion.
Celebrities took to Twitter to celebrate Weinstein's expulsion, with "Hellboy" actor Ron Perlman declaring how "proud" he was of the decision.
Mia Farrow, who worked with Polanski on "Rosemary's Baby" (1968) voiced hope that "we are witnessing the end of an awful era" while cautioning that "there are others".
Weinstein's films have received more than 300 Oscar nominations and 81 statuettes, according to The Weinstein Company, which he co-founded after selling Miramax.
The studio fired him on Sunday and is exploring a sale or shutdown, according to the Wall Street Journal.
Meanwhile the producer's wife, English fashion designer Georgina Chapman, has said she plans to divorce him.