Elliot Fletcher, 12, died after a Brisbane schoolyard stabbing in February.
Eight-year-old Trinity Bates was murdered in Bundaberg in the same month.
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Thousands of people paid tribute to the children on Facebook pages but the sites were soon defaced by hackers.
Queensland police said the anti-child exploitation task force Argos had on Friday charged a 29-year-old Tarragindi man over the defacing.
Detectives who executed a search warrant on a Brisbane home on Friday morning allegedly found child exploitation material.
The man faces five charges relating to the offensive use of the internet and possessing and distributing child exploitation material.
He is expected to appear in Brisbane Magistrates Court on Friday afternoon.
Detective Superintendent Peter Crawford said there was a clear message out of the case.
"You are not anonymous when online and you can and will be held responsible for your actions when they breach state or commonwealth legislation," he said.
