Cosby, 83, has served more than two years of a three- to 10-year sentence after being found guilty of drugging and violating Temple University sports administrator Andrea Constand at his suburban Philadelphia home in 2004.
He was the first celebrity tried and convicted in the #MeToo era.
Here's a look back at some of the key events leading up to Cosby's conviction and release:
Cosby meets Andrea Constand at Philadelphia's Temple University, his alma mater, where she manages the women's basketball team and he serves as a celebrity booster and trustee. (The Associated Press does not usually identify people who say they are the victims of sexual assault, but Constand has agreed to allow her name to be used.)
JANUARY: Cosby drugs and assaults Constand at his suburban Philadelphia home, according to her testimony at last year's trial. The defense says any sexual encounter was consensual and happened earlier. The timing is important because Cosby was charged only a few days before the statute of limitations was set to kick in. Cosby has said he gave her three blue pills to alleviate stress before lying on the couch with her and engaging in sex acts. Cosby was 66, Constand was 30.
JANUARY: Constand, now back home in suburban Toronto, tells her mother something happened with Cosby. They go to police, who suggest they record him on a phone call. On the call, Cosby said he engaged in "digital penetration" but refuses to say what pills he gave her. The case is referred to Pennsylvania authorities. Cosby lawyer Walter Phillips calls the allegations "pointedly bizarre."
FEBRUARY: Montgomery County District Attorney Bruce Castor announces that he will not charge Cosby. He considers the case weak, citing the yearlong delay, Constand's continued contact with Cosby, and the failure of other accusers now coming forward to have ever filed a police complaint.
MARCH: Constand sues Cosby for sexual battery and defamation.
NOVEMBER: Cosby settles the case after giving four days of deposition testimony about his affairs with young women over a span of 50 years. A confidentiality agreement prevents either side from discussing the case.
OCTOBER: Comedian Hannibal Burress calls Cosby a rapist in a standup act caught on video and shared online. More women accuse Cosby of assaulting them.
DECEMBER: The Associated Press petitions to have documents in Constand's 2005 lawsuit unsealed. Cosby fights the request.
JULY: U.S. Judge Eduardo Robreno grants the AP's motion, saying "the stark contrast between Bill Cosby, the public moralist and Bill Cosby, the subject of serious allegations concerning improper (and perhaps criminal) conduct, is a matter as to which the AP - and by extension the public - has a significant interest." The documents include deposition excerpts in which Cosby acknowledges giving a series of women pills and alcohol before sex.
AUGUST: Montgomery County authorities reopen the 2005 criminal case, aware the 12-year statute of limitations for aggravated sexual assault has not yet run.
DEC. 30, 2015: Cosby is arrested, enters a not guilty plea and is released on $1 million bail.
JUNE 5: Cosby goes on trial. In her opening statement, a prosecutor warns the jury that Cosby isn't the character he plays on TV. The defense counters by attacking Constand's credibility. The only other accuser permitted to testify at the trial, Kelly Johnson, describes an assault she says took place in 1996 at a hotel bungalow in Los Angeles.
JUNE 6: Constand testifies that Cosby gave her pills that made her woozy and then penetrated her with his fingers as she lay paralyzed on a couch, unable to tell him to stop. "In my head, I was trying to get my hands to move or my legs to move, but I was frozen," she says. "I wanted it to stop."
JUNE 7: Constand withstands hours of cross examination, dismissing any suggestion she and Cosby shared a romantic relationship before the night she says he assaulted her.
JUNE 8: Jurors hear Cosby's lurid, decade-old testimony in which he acknowledged giving quaaludes to women he wanted to have sex with and describes how he touched Constand's body during their sexual encounter: "I don't hear her say anything. And I don't feel her say anything. And so I continue and I go into the area that is somewhere between permission and rejection. I am not stopped."
JUNE 17: Jurors report they are hopelessly deadlocked, prompting the judge to declare a mistrial following more than 52 hours of deliberations over six days. Prosecutors immediately announce they'll put him on a trial a second time.
AUGUST: Cosby hires new lawyers, including Tom Mesereau, the high-profile attorney who won an acquittal in Michael Jackson's child molestation case.
JANUARY: Cosby performs in public for the first time since the scandal broke in 2015, taking the stage for about an hour at a Philadelphia jazz club.
MARCH: Judge Steven O'Neill agrees to let five additional accusers testify at the retrial, giving prosecutors a chance to portray Cosby as a serial predator who drugged and molested women. The defense argues that "ancient allegations" would confuse, distract and prejudice the jury.
APRIL 3: The judge gives Cosby's legal defense a huge lift by saying they can call a witness, Marguerite Jackson, who says Constand talked about framing a celebrity before she lodged sexual abuse allegations against Cosby in 2005. The judge also helps the defense case by ruling that jurors can hear how much Cosby ultimately paid Constand in the 2006 civil settlement.
APRIL 4-5: A jury of seven men and five women - 10 of them white, two of them black - is seated. Three of the six alternates are black.
APRIL 26: The jury convicts Cosby of three counts of aggravated indecent assault.
SEPTEMBER 25: Cosby was sentenced to 3-10 years in state prison.
Earlier in his sentence hearing, Cosby was declared a "sexually violent predator," a classification which means he will be considered a sex-offender and must undergo counseling for the rest of his life.
JUNE: In a stunning decision that could test the legal framework of #MeToo cases, Pennsylvania's highest court reviewed the trial decision to let five other accusers testify at Bill Cosby's sexual assault trial in 2018, which ended with the longtime TV star's conviction.
The Supreme Court agreed to review two aspects of the case, including the judge's decision to let prosecutors call the other accusers to testify about long-ago encounters with the actor and comedian. Cosby's lawyers had long complained the testimony was remote and unreliable.
The court also examined Cosby's argument that he had an agreement with a former prosecutor that he would never be charged in the case. Cosby has said he relied on the alleged promise before agreeing to give the deposition in trial accuser Andrea Constand's lawsuit.
In her first major interview in six years, Camille Cosby broke her silence after the Pennsylvania Supreme Court agreed to hear part of husband Bill Cosby's appeal to overturn his 2018 sex assault case.
MAY: Cosby was denied paroled after refusing to participate in sex offender programs behind bars. He has long said he would resist the treatment programs and refuse to acknowledge wrongdoing even if it means serving the full 10-year sentence.
JUNE: Pennsylvania's highest court threw out Bill Cosby's sexual assault conviction and opened the way for his immediate release from prison Wednesday in a stunning reversal of fortune for the comedian once known as "America's Dad," ruling that the prosecutor who brought the case was bound by his predecessor's agreement not to charge Cosby.
Four judges formed the majority that ruled in Cosby's favor, while three others dissented in whole or in part.
The Associated Press contributed to this report.