The striker saw his St James' Park contract terminated a fortnight ago after a series of scrapes with the law and is in trouble again after an altercation in Newcastle city centre
Ranger, who left the Magpies by mutual consent a fortnight ago, was detained after being involved in a scuffle in the car park of entertainment complex, The Gate.
Ranger has previously been in trouble for a number of alleged offences, including causing criminal damage, theft and being drunk and disorderly.
"At 7.09pm yesterday evening police received a report of a fight in the car park area at The Gate, Newcastle," a Northumbria police spokesman said.
"A 21-year-old has been arrested on suspicion of assault and he is currently in custody helping police with inquiries."
Ranger is set to appear at Newcastle Magistrates Court on Friday.