Only five years ago, his cultural influence was once so great that chat show queen Oprah Winfrey credited the now 81-year-old Cosby with helping to pave the way for America's first black president, Barack Obama.
More than 50 other women also have accused Cosby of sexual abuse going back decades, with most complaints too old to prosecute.
"This has been a long journey to justice for all of the accusers - particularly for Andrea Contand and her family", attorney Gloria Allred told reporters outside the courtroom in Norristown, PA, referring to the woman Cosby sexually assaulted in 2004.
The sentence ensures that Cosby will spend no less than three years behind bars before he becomes eligible for supervised release, though he could end up staying in prison for as much as a decade.
Prison officials will process Cosby at the nearby state prison in Schwenksville before determining in which of Pennsylvania's 22 male prisons he will serve his sentence, prison spokeswoman Amy Worden wrote in an email.More news: Liverpool players are being powered by ‘secret drink’ to boost fitness
As the allegations mounted, his career all but collapsed, "Cosby Show" reruns were taken off the air, and one college after another stripped him of his honorary degrees.
Women's rights activist and attorney Gloria Allred lauded the sentencing of Bill Cosby, saying it "has been a long journey to justice for all of the accusers".
Under Pennsylvania law, a sexually violent predator is someone convicted of a sexually violent offense who has a mental abnormality or personality disorder that makes the person likely to engage in predatory sexually violent offenses.
Constand, 45, said her training as a professional basketball player had led her to think she could handle anything, but "life as I knew it" ended on the night she said Cosby knocked her out with pills and penetrated her with his fingers as she lay almost paralyzed on a couch.
Defense lawyers had argued that Cosby should be confined to house arrest, as he has been since his conviction, arguing that he is too old and too frail - the actor says he is legally blind - to endure a correctional facility.
Consequently, Cosby was categorised as a sexually violent predator.More news: Canada refusing to make concessions on NAFTA
Andrea Constand says she's had to cope with years of unrelenting pain, anxiety and self-doubt after Bill Cosby drugged and sexually assaulted her at his home in 2004.
Addressing the victim, Judge O'Neill said, "I heard the very clear impact on your life".
Cosby was also labeled a sexually violent predator during his sentencing, meaning that he'll undergo counseling for the rest of his life. "He robbed me of my health and vitality, my open nature and my trust in myself and others", she wrote in the impact statement.
Constand said she now has trouble trusting people. Prosecutors questioned whether Foley got a complete picture of Cosby's alleged deviance.
When prosecutors told Cosby in court he would not have to inform Constand of his movements himself but that a proxy would do so, he replied: "Good!"
Prosecutors are asking for a sentence of five to 10 years in prison. Montgomery County District Attorney Kevin Steele said at a news conference, "Finally, Bill Cosby has been unmasked, and we have seen the real man as he is headed off to prison". His age and physical infirmities did not sway the judge or the prosecution. They argued that Cosby should serve his time on house arrest.More news: Tanushree Dutta accuses Nana Patekar of harassment on sets of 2009 film