Unemployed Philip Thompson, 27, amassed nearly a quarter of a million indecent pictures of children, including thousands in the two most serious categories.
He was jailed for a minimum of 45 months after pleading guilty to 27 child abuse charges at Teesside Crown Court in Middlesbrough.
Police said undercover officers have identified 360 suspects worldwide, made more than 50 arrests and saved 15 children from abuse during the long-running investigation.
British officers worked with colleagues around the world, including the United States, Canada and Australia.
Cleveland Police said the guilty verdict struck a "major blow" to online child abuse and should act as a deterrent.
"He was a senior administrator for a paedophile website and was effectively a librarian for the storing and distribution of indecent images of children," Detective Sergeant Rebecca Driscoll said outside court.
"Today's sentence reflects how seriously the criminal justice system views those who take gratification from the sexual abuse of children."
The Child Exploitation and Online Protection Centre (CEOP), a specialist police agency which helped the inquiry, said the trial followed the biggest deployment of undercover police in a child abuse case.
More than 130 of the suspects identified live in Britain and more arrests are likely.
The investigation began in May 2007 when London's Metropolitan Police paedophile unit began monitoring an Internet forum.
Users posted images of children that were on the fringes of the law and invited others to comment on them. Once contact was made with other paedophiles, they would exchange more explicit material through more secure online channels.
They hoped the tactic would keep their activity secret and help them to avoid arrest.
"This website -- whilst appearing to operate on the margins of legality -- was clearly a front for the sinister, sexual abuse of children and an image trading ground for paedophiles," said CEOP's Chief Executive Jim Gamble.