He will be registered as a sex offender for life.
That risk may be reduced by time in protection and in time, Pell may be able to mix with a limited number of heavily vetted prisoners, the commissioner noted.
Though not shortening his sentence, Judge Kidd said he did impose a shorter non-parole period "in recognition in particular of your age, so as to increase the prospect of your living out the last part of your life in the community".
The Cardinal has steadfastly maintained his innocence.
"I would be so disappointed if the Church did not accept mandatory reporting of child sexual abuse, which to date they have not", she added.
The victim, who has never been named, also rebutted criticism of the guilty verdict, saying he had spent more than two days giving evidence and was cross-examined by Cardinal Pell's defence lawyer - vigorously sources told Catholic News Service - while the cardinal did not take the stand at all.
A court artist sketch of Cardinal George Pell at the County Court in Melbourne.
Pell, who was until late-February the Vatican's treasurer, is the most senior member of the Catholic Church to be jailed for child sexual abuse.
The father of the other victim, who died of a drug overdose in 2014, said through his lawyer that Pell's sentence was "disappointing".
"Nor are you to be sentenced for any failure to prevent or report child sexual abuse by other clergy within the Catholic Church". His appeal hearing has been set for June 7-8, which critics claim is unfair as most inmates usually have to wait a year or longer before their challenging of a court verdict is heard. "Both victims were visibly and audibly distressed during this offending", he said, adding Pell's behaviour had a "nasty element" to it.
Live: Catholic Church Cardinal George Pell sentenced for sexual abuse of children
He was sexually abused by Pell in the priest's sacristy after a Sunday mass in December 1996, forced to watch as Pell molested his 13-year-old friend, and then molested again by Pell a month later.
"Thank you for your interest in this case", he said.
Australian police interviewed Pell about the survivor's allegations in a Rome hotel in 2016. Pell is one of them.
SNAP, a US support group for victim of clergy abuse, described the sentences as "comparatively light".
Kidd maintained, however, that Pell's sentence was given "without fear or favour", the Guardian reported.
According to the BBC, Pell plans to appeal the convictions.
He was actually convicted of five offences in December a year ago, but details of the verdicts were kept secret for fear they would prejudice a second trial he was facing.
More than 150 people crammed into the courtroom, which had been fitted with extra seats to cope with the demand from those who wanted to be there in person to hear how he'd be punished.
In sentencing Pell, Kidd considered the question of Pell's experience in prison due to his notoriety but dismissed the argument that the public broadcast of the decision presented further punishment, including behind bars, noting the case had already been highly publicized.