The movie production firm he co-founded, The Weinstein Company, said in a statement that its co-chairman’s employment had been “terminated, effective immediately”.
It said its board of directors made the decision “in light of new information about misconduct by Harvey Weinstein that has emerged in the past few days”.
Weinstein had taken a voluntary leave of absence after the allegations were detailed in The New York Times last week.
In a statement, Weinstein conceded causing “a lot of pain” and asked for “a second chance”, blaming his actions on the workplace culture in the ’60s and ’70s.
But he and his lawyers have also criticised the New York Times report, vowing an aggressive response.
The company’s board endorsed Weinstein’s leave on Friday, but went further on Sunday night, sacking the 65-year-old from the firm.
And a report in the entertainment website The Wrap said the company is considering changing its name following the allegations.
The Oscar-winning Weinstein was one of Hollywood’s most powerful producers.
He made his name with Miramax, the company he founded with his brother Bob in 1979 and which was eventually sold to Disney.
Miramax helped launch the careers of filmmakers including Quentin Tarantino and Steven Soderbergh, winning Oscars for best picture with Shakespeare In Love and The English Patient.
The Weinstein Company, which the two brothers founded in 2005, produced hits including The King’s Speech, Django Unchained and Silver Linings Playbook.
Also on Sunday, Donald Trump got involved in the scandal, saying he was “not at all surprised” to see the allegations of sexual misconduct made against Weinstein.
As he boarded a helicopter at the White House, the US President told reporters: “I’ve known Harvey Weinstein a long time… I’m not at all surprised to see it.”
The comments coincide with the anniversary of the publication of the 2005 Access Hollywood video in which Mr Trump boasted about grabbing women’s genitals.
The President again dismissed the tape’s contents as typical male bragging, saying – as he did at the time – “that’s locker room talks”.
His intervention comes after Weinstein’s latest accuser, TV presenter Lauren Sivan, claimed he cornered her in a Manhattan restaurant in 2007 and tried to kiss her.
When she refused, he said: “Well, can you just stand there and shut up.” He then allegedly performed a sex act in front of her.
She joins other women, including actors Ashley Judd and Rose McGowan, in accusing the film producer of sexual harassment stretching back years.
In another blow to Weinstein, his lawyer, Lisa Bloom, has quit representing him.
In a statement issued on Thursday, he apologised for his conduct, saying: “I appreciate the way I’ve behaved with colleagues in the past has caused a lot of pain, and I sincerely apologise for it.
“Though I’m trying to do better, I know I have a long way to go.”
Weinstein is married to British fashion designer Georgina Chapman. The couple have two children. Weinstein also has three children from his previous marriage.