The US comedian was found guilty at the Montgomery County Courthouse in Pennsylvania today.
The 80-year-old, who is awaiting sentencing, could spend his final years behind bars.
Bill could face up to 10 years in prison on each of the three counts of aggravated indecent assault.
The shamed star has been granted bail, pending sentencing.
As jurors left the courtroom, the comedian was said to have reacted angrily before using an expletive towards District Attorney Kevin Steele, who was arguing to revoke bail.
The guilty verdict came after a 14-hour deliberation from a jury panel of seven men and five women.
The case is the first major celebrity trial in the #MeToo era, which has raised awareness of alleged sexual assault by high-profile figures.
It came following a two-week retrial of a case against Bill, in which he was accused of drugging and sexually assaulting former basketball player Andrea Constand back in 2004.
The actor previously stood trial for the allegations, however a jury failed to deliver a verdict back in June last year.
Bill, who has denied Ms Constand’s claims, paid the 45-year-old almost £2.4 million in a civil settlement back in 2006.
The actor’s lawyer called Ms Constand a “con artist” who levelled false accusations against Bill in order to sue him.
Bill previously denied the charges, claiming that sexual relations had been consensual.
The actor acknowledged giving pills to Ms Constand before their sexual encounter, however he said they were over-the-counter cold and allergy medicine Benadryl.
The Bill Cosby Show star insisted they had been intended to help her relax.
More than 60 women over a span of five decades have previously publicly accused the actor of drugging and molesting them.
However, statute of limitation laws meant that just one charge was brought to trial.
The actor is known for having starred in his own American sitcom, The Cosby Show, between 1969 and 1971.
The father-of-five shot to fame back in the 1960s, as he appeared in the NBC adventure series I Spy.
It was revealed back in February this year that Bill’s daughter Ensa Cosby had died at the age of 44.
A spokesperson told People, Ensa died of kidney failure.
A statement released on behalf of her family read: “The Cosby Family thanks many people for their prayers for their beloved and beautiful Ensa, who recently died from renal disease.”