Emerton, of Berkhamsted, Hertfordshire, later admitted further offences including conspiring with the other defendants in order to rape, commit sexual activity with a child or engage in sexual activity in the presence of a child.
He was given a further two life sentences.
The judge said he had caused psychological trauma to the children who will face a "lifetime of difficulties".
Other members of the gang included Matthew Webby, 30, from Hemel Hempstead, Robert Lindsay, 39, from Markyate, Paul Stevens, 54, from Northchurch, Simon Wintle, 44, from Hemel Hempstead and Thomas Perry, 28, from Northchurch.
Stevens was sentenced to 10 years with a five year licence extension, Webby was sentenced to nine years with a five year licence extension, Lindsay was sentenced to five years three months with a three year licence extension, Wintle was sentenced to two years six months.
Perry will be sentenced on January 24.
Judge Michael Kay QC told the perverts their crimes were so shocking they undermined his faith in humanity.
He said: "It is a sad feature of life as a judge in the criminal court, and for other involved in the criminal justice system such as the police, the lawyers and the probation officers, that one has time and again to read about and sift through the evidence and detail of sexual depravity, very often involving children.
"Even within this field of appalling and sickening abuse, there is from time to time a case which is so shocking that it undermines one's faith in humanity. This is one such case.
"Never before have I read a police summary of a case which begins with a warning that the reader should be very wary of the content due to the abhorrent nature of the offending."
The police investigation, codenamed Operation Pendent, was the largest ever conducted by the Hertfordshire Child Online Safeguarding Team (COST).
Chief Inspector Dee Perkins said after the sentencing: "This was an extensive inquiry which resulted in the sharing of intelligence with more than 50 other law enforcement agencies.
"Emerton, the paedophile at the centre of this investigation, mercilessly exploited children for his own sexual gratification and for those other men who he met online.
"The nine life sentences he has received reflect the disturbing nature of his actions. Work is ongoing to support the victims and make sure they have the best possible chance of a normal life ahead.
"Not only was this a large and complex investigation but also one that involved working through a large amount of video evidence in which this group had documented their own horrific crimes.
"Our reward is to see these men behind bars today and for many years ahead."
Helena Burman, Senior Crown Prosecutor for Thames and Chiltern Crown Prosecution Service (CPS) said: 'This case involved the serious and sustained sexual abuse of vulnerable young children by a ring of active paedophiles.
"The young age of the victims greatly increases the seriousness of the offences. As a result of the hard work and diligence of the prosecution team, and the strength of the evidence, four of the defendants pleaded guilty and the fifth was found guilty after trial.
"It is only due to the great courage of the victims that this abuse was brought to light, and the full extent of the despicable and lawless behaviour of these people revealed.
"I know that nothing can undo what happened to the victims, but I hope that the convictions and today's sentences will give them, with the passage of time and appropriate support, at least a small sense that justice has been done. My thoughts are very much with them at this time."
James R. Mancuso, attaché for Homeland Security Investigations (HSI) in London said: "Protecting children from exploitation is one of the most important missions we have, and as this case demonstrates, it takes the collaboration of law enforcement agencies around the world to tackle this crime."
A spokesman for Hertfordshire Police said: "In one instance, intelligence was shared via the National Crime Agency with the Department of Homeland Securities about a potential offender in the USA.
"The intelligence suggested there was an immediate risk of harm to a potential victim. The suspect was detained in custody by American authorities within 48 hours of the evidence of offending being discovered in the UK."
