The arrests took place during the past five months in a joint operation between the PSNI and the National Crime Agency (NCA).
It is the first joint operation of its kind since the NCA began operating in the province in May.
Four people have been charged, including one who had “extreme pornographic images”, and action taken to protect 32 children deemed to be at risk during the probe which was codenamed Operation Jarra.
The investigation targeted people using the internet to access indecent images of children.
Detective Chief Supt George Clarke, head of the PSNI’s Public Protection Branch, said it was a “despicable crime”.
“What we are talking about here is people viewing imagery of children being raped, being brutalised, and being physically abused,” he added.
“This criminal activity touches every part of Northern Ireland, and every part of society here, and we have some very dangerous offenders here.”
He also had this warning for those involved in this kind of crime.
“Offenders need to know the internet is not an anonymous place, it is not a safe place, it is a place where law enforcement is looking for them, where law enforcement is going to find them, and they will face the full rigour of the law when caught,” he said.
Dr Zoe Hilton, Head of Child Protection for the NCA, said more arrests will follow.
“We want to send a very clear message that people are not safe anywhere on the internet if they are looking at indecent images of children,” she said.
“They are leaving a forensic trail and we will find them. There is no hiding place.”
Dr Hilton said the sexual exploitation of children on the internet has a serious and long lasting impact on the victims.
“Online images are not a ‘lesser’ form of abuse,” she said.
“Every child in those images has been sexually abused, and every time someone looks at an image that child is victimised again.
“Knowing those images are out there has a devastating impact on victims.”