Prosecutors asked for five to 10 years behind bars, saying he could still pose a threat to women.
But that legacy was buried forever on Tuesday when a judge sentenced him to a minimum of three, and a maximum of 10 years in prison for drugging and molesting a former basketball player at his Philadelphia mansion 14 years ago.
"This was a serious crime", said O'Neill, a judge in Montgomery County, Pennsylvania.
Dozens of women have accused Cosby of sexual misconduct during his 50-year career in entertainment.
Ms Constand, now 45, said she has suffered with anxiety and self-doubt for years in a statement submitted to the court. The now frail entertainer was slapped in handcuffs, and led out of court in his shirt and braces, his tie and jacket removed.
"This should be a state prison sentence", said Steele, who said the state even has a prison facility for old and infirm inmates.
Cosby's defense said earlier they plan to appeal his conviction.
It was the first celebrity trial of the #MeToo era.
Constand's was the only case that was within the statute of limitations, and is so far the only criminal case filed against him.
Being now ruled as a sexually violent predator, Bill Cosby name will now appear in sex-offender registry which will be further circulated to schools, victims and in textbooks.
Cosby had remained on house arrest since his conviction.
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After the sentencing, the judge took a break to consider the defense attorney's request to free Cosby on bail during the appeal.
"I wanted 30 years, but I'm very happy to know Mr. Cosby will do time in prison", said Chelan Lasha, who gave tearful testimony in court about the time she says Cosby drugged and groped her in the 1980s.
"It's been a long journey to get here and today justice was served".
Five other accusers took the stand at the trial as part of an effort by prosecutors to portray him as a predator.
O'Neill also fined Cosby $25,000 and ordered him to pay the costs of the prosecution.
Cosby is still in court and sentencing is expected at any moment, stay tuned.
Constand, who is now a massage therapist in Canada, testified during the trial in April and in an earlier trial past year that ended with a hung jury, that she had become friends with Cosby, and viewed him as a mentor.
His decision to designate Cosby a predator means the once-beloved star known as "America's Dad" will have to undergo monthly counseling and register as a sex offender with police for the rest of his life.
Constand writes in a victim-impact statement released Tuesday that Cosby's 2004 attack on her was just "the tip of the iceberg" for the suffering that followed.
She said she lived alone with her two dogs and had trouble trusting people.
Cosby did not testify at trial. They argued that Cosby - who is legally blind - is too old and weak to do time in prison.