He claimed the encounter was consensual. Montgomery County District Attorney Kevin Steele, who resurrected the criminal case after his predecessor opted against bringing charges and who forged ahead with a retrial after Cosby's first trial ended with a deadlocked jury, described Cosby as a "man who had evaded this moment for far too long".
He faces up to 30 years in prison.
Shortly after the guilty verdict was announced, several accusers immediately celebrated outside the courtroom. Constand remained stoic, then hugged her lawyer and members of the prosecution team.
Andrea Constand took the stand for a second time in a retrial over Cosby's drugging and raping of her at his Philadelphia home in 2004.
He added: "Now, we really know today who was really behind that act, who the real Bill Cosby was".
"And all women that are out there standing up and telling their truth, I, we, support them and encourage them to keep it up", said Steele.
Bill Cosby's spokesman says the 80-year-old comedian is feeling great, and confident he did nothing wrong, one day after being found guilty on three counts of aggravated indecent assault.
"The rules have been changed to allow prosecutors to present other accusers besides those that are the basis of the charge", he says. "It's finally time for the defendant to dine on the banquet of his own consequences".
"While the #MeToo movement might have opened the floodgates of sordid stories and reveals how ubiquitous the experience of such abuses of power are, the outcome of Cosby's trial underscores the sad truth that the voice of a single woman too often isn't enough", The Philadelphia Inquirer said in an editorial.
Clearly, this wasn't going to be your grandmother's Cosby trial any more.
To Lotte-Lublin, who wasn't permitted to testify in the first trial, the new witnesses' testimonies were in sync with Constand's testimony. Cosby's lawyers slammed #MeToo, calling Cosby its victim and likening it to a witch hunt or a lynching.More news: Washington in uproar over 'disgusting' White House Correspondents' dinner comedy routine
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Many on social media applauded the #MeToo movement as a factor in propelling this case, involving a high profile figure, to the point of conviction.
"I'm overcome with gratitude", Bernard, sobbing, said outside the courthouse.
"I could not fight him off", she testified. Cosby later paid $3.4 million to settle the suit.
But Cosby had long ago confirmed some of the rumours about drugs and extramarital sex.
Even before the verdict, more than 20 colleges and universities across the US had revoked honorary degrees from Cosby in light of allegations against him.
"I wanted to see what he looked like again, in person, and it was just frail, and sad, and just a little bit kind of pitiful", she said. But he identified them as the over-the-counter cold and allergy medicine Benadryl and insisted they were meant to help her relax.
The entertainer broke racial barriers as the first black actor to star in a network show, "I Spy", in the 1960s.
Lotte-Lublin realized she had been assaulted by Cosby after the first allegations surfaced in November 2014. He also found success with his "Fat Albert" animated TV show and appeared in commercials for Jello-O pudding.
He had been "foolish" and "ridiculous" in being attracted to a younger woman but he was no criminal.
It was Cosby's reputation as a public moralist that prompted a federal judge, acting in response to a request from The Associated Press, to unseal portions of the deposition. The case was reopened in 2015. Constand has done so.