The New Zealand international, a member of the Panthers' 2003 premiership-winning side, was under contract until the end of 2009 but asked the club for a release last month.
Puletua, 28, will link up with former St George fullback Mick Potter, after the club announced he would replace Daniel Anderson as coach from next season.
"Tony has been a great ambassador for the Panthers," chief executive Michael Leary said in a statement.
"It will be sad to see him leave and we wish him and his family all the best.
"I know Tony will play out the rest of the season by producing some of his best football for the Panthers."
Puletua has played 195 games for the Panthers since making his first grade debut in 1997, making 18 Tests appearances for the Kiwis.
He had also been linked with a move to Hull.Like