The man, 42, masqueraded as the Canadian singer to gain explicit images from children, Queensland Police said.
He was charged with 931 crimes, including three of rape, involving 157 alleged victims across the globe.
Detective Inspector Jon Rouse called the allegations “frankly horrendous” and warned young fans of the singer and parents to be vigilant.
“The fact that so many children could believe that they were communicating with this particular celebrity highlights the need for a serious rethink about the way that we as a society educate our children about online safety,” said Mr Rouse.
Queensland Police confirmed the investigation also involved international authorities. According to local media they are German police and US Homeland Security.
Of the alleged victims, 50 were in the US, up to 20 were in the UK and six were in Australia, police said. More precise information was still being gathered.
The man was already facing charges in Queensland of possessing exploitative material and grooming children, but the 931 charges were added this week after police searched his computer.
He had been using “multiple online platforms” including Facebook and Skype to communicate with children, police said.
The fresh claims, dating back to 2007, include three charges of rape and five of indecently treating a child under 12.
Mr Rouse said the allegations showed “the global reach and skill that child sex offenders have to groom and seduce victims”.
He urged parents to help keep children safe online.
The accused man will face a Brisbane court on 6 April.
|Charge||Number of alleged offences|
|Indecent treatment of children||5|
|Making child exploitation material||272|
|Using a carriage service to menace, harass or cause offence||9|
|Using a carriage service for child pornography material – causes to be transmitted to oneself||29|
|Using a carriage service for child pornography material – transmits/promotes||3|
|Using a carriage service for child pornography material – solicits||231|
|Using a carriage service to procure persons under 16 years of age||240|
|Using carriage service to groom persons under 16 years of age – act in front of sender||92|
|Using carriage service to groom persons under 16 years of age||39|
|Using carriage service to transmit indecent communication to person under 16 years of age||7|
|Use a carriage service to access child pornography material||1|
|Source: Queensland Police|