She testified that she began to feel dizzy and sick and ended up in his hotel room.
"He got on top of me, she said. “I was seated at the edge of the bed. He smelled like cigars and espresso. I couldn’t move."
Cosby, 80, is charged with three counts of aggravated indecent assault against Andrea Constand, a former employee of Temple University, who alleges that he drugged and molested her in his suburban Philadelphia home in 2004.
Cosby has repeatedly denied all the allegations against him, and has said the sexual encounter with Constand was consensual.
Dickinson was the fourth woman to testify against Cosby in the Montgomery County Court of Common Pleas in the last two days. Cosby is not charged in any of the assaults alleged by the four women, who are being allowed to testify to give the prosecution a chance to establish that the assault alleged by Constand fits a pattern.
When asked by defense attorneys why she never reported the assault to police, Dickinson said she feared that going public would ruin her career.
“I was a famous model and I had conservative clients,” she said. “Clients that would not appreciate the fact that I had been raped."
Defense attorney Tom Mesereau grilled her about why the story of the assault did not appear in her 2002 memoir, “No Lifeguard on Duty: The Accidental Life of the World’s First Supermodel.”
She replied that her ghostwriter convinced her to leave details of the assault out of the book, suggesting that challenging a powerful man like Bill Cosby was not in her best interests.
She also pointed out that when she wrote the book, she was not under oath, as she was before the jury. “I was broke, I needed to pay for my children’s education,” she said.
Mesereau also accused her of spreading false rumors about being pregnant with Sylvester Stallone's child.
Dickinson suggested that her remark had been an honest mistake.
"I had sex with two men that month," she said. "He wasn't the only contender," she added, garnering smiles from the jury.
But most of the time, the mood was tense both inside and outside the courtroom.
In front of television cameras, an argument broke out on the steps of the courthouse between Cosby’s publicists, Andrew Wyatt and Ebonee Benson, and Gloria Allred and her daughter, Lisa Bloom, attorneys representing most of the women who testified on Wednesday.
Benson and Wyatt called the two lawyers “con artists," and accused Allred of telling the other women with complaints against Cosby that they would get rich.
“Is she helping these women pro bono? The question is, what has she promised them?” Benson said.
Allred retorted: "You can have your highly paid defense attorney Mr. Mesereau ask them any questions they like."
Benson was referring to a 2014 proposal by Allred that $100 million be aside for victims who could prove their claims at trial or in arbitration. Allred said, however, that Cosby never accepted the terms of the agreement.
Cosby's first trial last year ended in a mistrial after a jury deliberated for 52 hours and failed to reach a verdict.