He will now have to have counseling every month for the rest of his life, and report to authorities every quarter.
The actor's defence team had argued the state's sex offender law was too severe given Cosby's age, as well as the fact that he is legally blind.
At a retrial in April, Cosby was found guilty of three counts of sexual assault against Andrea Constand.
Constand spoke briefly on the first day of the hearing on Monday, saying "all I am asking for is justice as the court sees fit".
The judge quoted from victim Andrea Constand's own statement to the court, in which she said Cosby took her "beautiful, young spirit and crushed it".
Because he was convicted on three counts of assault, Cosby had faced up to 30 years in prison for the charges.
The sole defense witness, Timothy Foley, a psychologist, testified that he believed the entertainer's risk of assaulting another person was "extraordinarily low".
But social media also was rife with comparisons between Cosby and President Trump, disgraced NBC host Matt Lauer, accused former Hollywood executive Harvey Weinstein and others accused of sexual assault or sexual improprieties but not convicted.
Cosby is the first celebrity of the #MeToo era to be sent to prison.
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!" Cosby's legal team alternatively has requested the once beloved television star, now 81 and legally blind, be placed on house arrest as he does not pose a risk to the community.
Cosby's name will now appear on the sex-offender registry. Asked if he wanted to address the court with a statement before sentencing, Cosby declined through his lawyers.
On Monday, Green urged Judge Steven O'Neill to ignore the protests and activism surrounding the case and send Cosby home.
Green rejected the prosecution's contention that Cosby should be considered unsafe, saying he couldn't recall any instance in which an 81-year-old, blind defendant had been sent to state prison.
She testified that Cosby has a mental disorder that attracts him to non-consenting women, and that "he is likely to re-offend".
The spokesman further added: 'I'm not saying Mr Cosby is Jesus, but we know what this country has done to black men for centuries.
The AP does not typically identify people who say they are victims of sexual assault unless they come forward publicly, which Toronto-based Constand and other women have done.
"So it's taken a long time to get there", Steele said. His body of work developed his legacy as "America's Dad", in particular his depiction of obstetrician Cliff Huxtable on The Cosby Show, which ran for eight seasons until 1992.
The comedian's first trial in 2017 ended in a hung jury.