Pearce has been strongly linked to an immediate move to French Super League club, Catalans Dragons, to finish out his professional career.
The 32-year-old formally asked for a release from the Knights last month after meeting with club powerbrokers.
Newcastle announced that Pearce had been released effective immediately, so he could take the French deal with a reported $1.8 million over three years.
“The Newcastle Knights have agreed to grant Mitchell Pearce a release to join English Super League Club, Catalans Dragons,” a club statement read.