One complainant, with a severe intellectual impairment, recalled feeling "scared" when the offending began and said she never told anybody because she thought she may get in trouble.
Another complainant testified she saw the man sexually abusing another female with impairments so severe she was unable to talk.
"I heard her making her noises ... so I went down [the hallway] and he was on top of her."
A deliberating for just under six hours a jury found him guilty of five charges of sexually exploiting a person with as significant impairment, five of rape, two of sexual conduct with a child under 12 years old, and one each of attempted rape, indecent assault and unlawful sexual connection.
At sentencing this morning Judge Bridget Mackintosh noted the man continued to deny the offending.
"You maintained you would never harm 'your girls', as you described, in such a way ... and described being completely dumbfounded when first presented with the allegations, and that this whole process has disturbed you greatly."
Ms Rielly asked for a starting point of 18 years' imprisonment, asking the Judge to consider a number of aggravating factors of the offending.
"What cannot escape the court in sentencing [the defendant] is the extreme vulnerability of the victims, the significant breach of trust and also ma'am, in respect to [one complainant], the significant impact this offending has had in her life, and on her future," she said.
Judge Mackintosh accepted the vulnerability of the complainants as a significant factor, alongside the defendant's breach of trust and his lack of remorse.
"This offending has had a significant effect on her and it is going to take a lot of working through in the future. She's emotionally and psychologically scarred by what occurred to her."
The defendant's family filled the public gallery, as they did during the trial, and he leaned over the rail to speak to them as he was led from the dock after sentencing.
One family member abruptly left the courtroom saying, "I love you. I know you're innocent."
At the trial defence lawyer Scott Jefferson called several witnesses known to the defendant who each told the court they had never seen anything untoward about his behaviour towards those in his care.
But Ms Rielly said these testimonies, while well-meaning, seemed "contrived" and asked the jury to consider the fact the alleged abuse had happened when no one else was around.
"It's clear that all of the defence witnesses love the defendant, care about him and respect him. It's also clear he has done a lot of good for his family and community over the years ... but what I'd say to you is many otherwise good people do bad things."
Ministry for Vulnerable Children Oranga Tamariki inherited some CYF functions as of April 1 this year.
Regional manager Wellington-East Coast Grant Bennett said he was pleased with the outcome of the case.
"It is abhorrent that someone who was supposed to be providing care abused that position, and the sentencing reflects that. It is also very important from the perspective of the children involved who laid the complaints and testified."
He said Oranga Tamariki caregiver checks and policy were now more robust than they were when the defendant was first approved as a carer.
"As soon as the young person made the disclosure she was immediately uplifted and brought into CYF custody. She remains in the care of Oranga Tamariki and is receiving intensive clinical support."
Judge Mackintosh passed a minimum non-parole period of seven years' imprisonment.
