"I was called to meet Harvey Weinstein at the Savoy Hotel when I was 17," she wrote in an Instagram post.
"I assumed it would be in a conference room which was very common. When I arrived, reception told me to go to his room. He opened the door in his bathrobe."
"I was incredibly naive and young and it did not cross my mind that this older, unattractive man would expect me to have any sexual interest in him. After declining alcohol and announcing that I had school in the morning I left, uneasy but unscathed."
Kate went on to say that a few years after that incident, Harvey asked her whether he had "tried anything" with her that night. "I realised he couldn't remember if he had assaulted me or not," she wrote.
"I said no to him professionally many times over the years - some of which ended up with him screaming at me calling me a c*nt and making threats, some of which made him laughingly tell people oh 'Kate lives to say no to me,'" she continued.
"It speaks to the status quo in this business that I was aware that standing up for myself and saying no to things, while it did allow me to feel uncompromised in myself, undoubtedly harmed my career and was never something I felt supported by anyone other than my family. I would like to applaud the women who have come forward, and to pledge that we can from this create a new paradigm where producers, managers, executives and assistants and everyone who has in the past shrugged and said 'well, that's just Harvey /Mr X/insert name here' will realise that we in numbers can affect real change."
The 44-year-old also revealed that once her friend had tried to warn a young woman about Harvey, only to receive a call telling him he would never work another Miramax film - "The girl was already sleeping with Harvey and had told him that my friend had warned her off."