Cameron Flynn Tully has been jailed for 14½ years for abusing young girls he supervised as their parents met for religious instruction at his family's "Hillview" farm.
He will serve at least nine years and be eligible for release in June 2023.
Victims and their families embraced in a subdued display outside court after Justice John Burns on Friday sentenced Tully, 40, on the 18 counts of rape and acts of indecency against the eight children.
Neil Abraham, spokesman for the victims and their families,
said the victims would have liked a longer sentence but hoped they could move on with their lives.
"For so many years, the girls just had no-one believe in their stories, no-one did anything about it," Mr Abraham said.
"But finally, thanks to the Federal Police and the prosecutors, justice has been served today, we're just so thankful.
"No-one's joyful or bouncing around, it's a very solemn day, but there's a lot of relief and a lot of tears.
"We're glad we've finally all made it, had the strength to get here."
Tully did not react as the judge handed down sentence.
But his wife, Kathleen, wept as he was led away by guards.
Outside court, she pledged to lodge an appeal against the conviction.
She said he had her "unwavering and constant" support in what she described as a "miscarriage of justice".
"There was no evidence presented to support these allegations that supposedly happened over 20 years ago," Mrs Tully said.
"Cameron is my husband, he is my best friend, … I wholeheartedly believe in him.
"We have not finished fighting these malicious lies. We will never give up the fight to prove his innocence. We will absolutely lodge an appeal."
In June, an ACT Supreme Court jury found Tully guilty of abusing eight young girls in the 1990s and early 2000s while their parents gathered as part of a religious group.
Tully always denied the claims and believes the victims had wanted to tarnish his and his family's reputations.
Much of the abuse happened at the Tully family farm in West Belconnen but also extended into some of the children's homes.
The children would go the property when their parents met for church and community groups, and Tully would supervise them.
The girls, as young as four, were abused in the shearing shed, laundry, library and bedrooms in the farm's main rammed-earth building.
One was lured into a room with the promise of a kitten and two indecently touched as Tully gave them a piggyback ride.
Twelve impact statements were read at a September sentencing hearing, in which the victims described suffering feelings of anger, depression, anxiety and helplessness, which had pursued them into their adult lives.
The court was toldon Friday that a pre-sentence report author had assessed Tully as a moderate risk of sexual reoffending.
In handing down sentence, Justice Burns said Tully had used his position of power to gain access his victims, who had suffered "great and lasting harm".
The judge said the offences had not been isolated but instead were a pattern of behaviour over a decade.
"Your offences were brazen, revealing an arrogant belief that your victims would not report you or would not be believed if they did," Justice Burns said.
"You chose your victims because of they were young and vulnerable.
"Your refusal to accept responsibility for your crimes means … I cannot be satisfied that you will not reoffend."