Corrections have seized a cell phone and makeshift tattoo guns from prisoners at Rimutaka Prison after videos were posted to YouTube from inside.
A video was posted to YouTube and widely circulated last week, with Corrections becoming aware about 9.15am today, they said in a statement.
The videos, seen by 1 NEWS, show a prisoner tattooing another, inmates rapping, and what appear to be members of the Mongrel Mob singing and chanting.
Within 45 minutes, the two prisoners in the video had been identified and segregated and a search operation had commenced.
The tattoo gun was found and removed on Monday during routine searches, they said, while the cell phone was found yesterday and will be forensically examined.
"The prisoners are being held to account for their behaviour," Corrections' chief custodial officer Neil Beales said.
"All four were relocated to the management unit and are being charged with misconduct.
"Today, two of the prisoners have been moved from the prison, with plans being made to relocate the other two.
"Corrections jurisdictions worldwide face the issue of contraband being smuggled into prisons.
"In recent years we have strengthened the tools and methods we use to detect and recover contraband before it comes into prisons.
"As technology evolves it is a constant challenge to stay one step ahead of offenders."
Mr Beales said Corrections has contacted YouTube and asked for the footage to be removed.
"We appreciate that any images of prisoners available online will be of particular concern to the victims of offending."