The former Australian international signed for the Perpignan club ahead of the 2015 season, and scored six tries in 18 games for the Dragons.
The club have released him from his contract and reached an agreement with Leigh regarding his departure, according to club CEO Christophe Jouffret
“We are satisfied to have reached an agreement with Leigh for the transfer of Willie Tonga, who had one more year on his contract with us,” he said.
“Willie was not in our head coach’s plans and will add some quality to the Centurions squad.
“He is among the most decorated players we have had at the club and we wish him all the best with his new club.”