Neville Joseph Knight, also known as Neville Roughan, worked at two Police Citizens Youth Clubs in rural NSW when most of the indecent acts and assaults occurred.
The now-74-year-old worked as a boxing trainer at one club and later moved to Sydney before returning to help establish a PCYC in another country town.
He met eight of his victims through the youth centres.
Knight's sister Katherine was the first Australian woman jailed for life after murdering her husband and skinning him before boiling his head and cooking his buttocks as a meal.
On Wednesday, the elderly man watched from Long Bay prison, audibly sobbing and his body shaking as he was handed a maximum 18-year jail term at Sydney's Downing Centre District Court.
"No, no, no," he cried as his crimes were described in graphic detail.
When Judge Timothy Gartelmann said Knight would receive a 20 per cent discount for his guilty pleas, one of his victims screamed out in anger from the court's public gallery.
"You're a f***ing dead man, I'm going to have you killed," the man yelled.
Dramatic scenes played out in court as a prison sentence was handed down for decades of offending. (Mick Tsikas/AAP PHOTOS)
Knight met an Indigenous boy aged either 12 or 13 at the PCYC and sexually assaulted him in Sydney's west, at one time becoming enraged when the boy brought home a girlfriend.
He also sexually abused the boy's younger brother who was aged nine or 10, for which he later apologised, Judge Gartelmann said.
"He said he wanted redemption, forgiveness and did not want to die and go to hell."
Another boy, who confided in Knight that he had previously been sexually assaulted, woke to find the youth worker in his camp bed.
A seven-year-old youth, whose mother was addicted to heroin, would visit the PCYC for food and video games.
Knight offered him money on two occasions in exchange for sex.
An 11-year-old boy whose mother was an alcoholic also attended the youth centre, where Knight told him to grab $20 notes placed down his underwear and abused him at his granny flat.
In 2001, his sister-in-law found a recording of the man apologising for what he had done to this victim.
His molestation of another victim for money, cannabis and cigarettes continued even after the boy acquired a brain injury during an accident.
In the early 2000s, he would let boys from a nearby school smoke cannabis, watch DVDs and play video games at his home, abusing another youth at that time.
In sentencing Knight, Judge Gartelmann acknowledged the harm done to the victims.
"Each suffered fear and anxiety, and a sense of guilt and shame," he said.
The 74-year-old had shown remorse prior to his July 2021 arrest and had also been "visibly wracked" when the victim impact statements were read in court, the judge found.
Knight will be eligible for parole in November 2031.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028