Prosecutors in Los Angeles declined to charge Bill Cosby with sexually abusing two teenagers in 1965 and 2008, citing time limits and a lack of evidence.
The decision comes about a week after Cosby, 78, was charged with drugging and sexually assaulting a woman in 2004 inside his home near Philadelphia.
It was the first criminal case brought against him from the torrent of allegations that destroyed his good-guy image.
His lawyers have called the charges in that case unjustified and said they expected Cosby to be exonerated.
"We are satisfied that the Los Angeles DA's office fully and fairly evaluated all the facts and evidence, and came to the right conclusion in declining to file charges against Mr Cosby," his lawyer, Monique Pressley, said.
Dozens of women have accused Cosby of sex assaults or attempted molestations in incidents dating back more than four decades.