The actress and supermodel said she had the encounter with the movie mogul after a meeting with him and a film director in a hotel lobby.
She posted a statement on Instagram with a picture reading: “Don’t be ashamed of your story, it will inspire others.”
In it she described how after the director left the meeting Weinstein allegedly immediately began speaking of things of a sexual nature.
She wrote: “As soon as we were alone he began to brag about all the actresses he had slept with and how he had made their careers and spoke about other inappropriate things of a sexual nature.
“He then invited me to his room.”
Delevingne said that she quickly declined and asked if her car was outside.
When Weinstein’s assistant said it was not and suggested the model go to his room the actress was left feeling “very powerless and scared”, but hoped that she was wrong about the situation.
She continued: “When I arrived I was relieved to find another woman in his room and thought immediately I was safe.
“He asked us to kiss and she began some sort of advances upon his direction.
“I swiftly got up and asked him if he knew that I could sing. And I began to sing....I thought it would make the situation better....more professional....like an audition....I was so nervous.
“After singing I said again that I had to leave.
“He walked me to the door and stood in front of it and tried to kiss me on the lips. I stopped him and managed to get out of the room.”
Delevingne added that she still got the role in the film, adding she “always thought that he gave it to me because of what happened”.
She continued: “Since then I felt awful that I did the movie. I felt like I didn’t deserve the part.
“I was so hesitant about speaking out....I didn’t want to hurt his family. I felt guilty as if I did something wrong.
“I was also terrified that this sort of thing had happened to so many women I know but no one had said anything because of fear.”
In a second post, which contained the quote “The devil whispered in my ear, ‘you’re not strong enough to withstand the storm.’ Today I whispered in the devils ear, ‘I am the storm’”, she added: “I want women and girls to know that being harassed or abused or raped is NEVER their fault and not talking about it will always cause more damage than speaking the truth.
“I am relieved to be able to share this.
“I actually feel better and I’m proud of the women who are brave enough to speak.
“This isn’t easy but there are (sic) strength in our numbers.
“As I said, this is only the beginning. In every industry and especially in Hollywood, men abuse their power using fear and get away with it. This must stop.
“The more we talk about it, the less power we give them.
“I urge you all to talk and to the people who defend these men, you are part of the problem.”