When police confiscated Johnsson’s computer, they found 514,216 images as well as 10,239 films featuring child pornography, according to the Aftonbladet newspaper
Some of the material included documented cases of the rape of an infant.
Johnsson was also facing charges for sexually abusing four children in the Philippines in 2010.
On Tuesday the 45-year-old was convicted of aggravated pornography crimes, child rape, aggravated exploitation of a child for sexual posing, as well as conspiring to commit child rape by the Kristianstad District Court in southern Sweden.
Johnsson, from Skåne, in southern Sweden, was arrested in February on suspicion of child pornography crimes.
He was discovered after an American raid against an internet site for child pornography, as police discovered that the Swedish man was a frequent visitor of the site.
When police began to look into the case, they uncovered that he had also abused young children in the Philippines.
He was convicted of abusing four children in the Philippines, between the ages of 4 and 15, on visits to the country in 2010.
According to AFP, Johnsson had already purchased a flight back to the Philippines, and online chat records indicated that he intended to sexually assault more children.
This is the third case in which someone in Sweden has been sentenced for child abuse crimes committed in another country.
“This is a very strong signal we’re sending. Just because the crimes weren’t committed in Sweden, we can still arrest a suspected paedophile, and then charge them with the crimes,” said criminal inspector Björn Sellström of the National Bureau of Investigation (Rikskriminalen) to national Sveriges Television (SVT).
Helena Karlén, chairwoman of the organisation Ecpat, is pleased that politicians and police authorities are beginning to take this type of child abuse abroad seriously.
“It’s important that the public are made aware of these crimes, and that people know that abuse on the other end of the globe can lead to a conviction back home in Sweden,” she told TT.
“The media’s attention on these cases is positive. It can act as a deterrant.”
The 45-year-old has denied all charges against him except the pornography crimes.