Leigh have bolstered their pack with the addition of two players from the NRL.
Stone, who has signed a contract that runs to the end of 2022, makes the move with encouragement from his father Rick, who coached in Super League with Huddersfield from 2016-18.
“I’ve always wanted to play in England and I think the style of footy will be great for me,” said Stone, a former Junior Kangaroo who has also played for Newcastle Knights.
“The game in the NRL is very conservative and the English game is much more open and as a player you have the opportunity to express yourself.
“My dad said I should go for it and he encouraged me to sign. After I had spoken to the owner and the coach at Leigh, I was excited after hearing of their enthusiasm and their plans for the future.
“It will be my first time coming to the UK and I can’t wait to get over as soon as possible, rip in and help the club get a few wins before the end of the season.”
Leigh interim coach Kurt Haggerty said: “We are very pleased to have Sam on board. He is a player who we have monitored closely and it’s great to finally get the deal over the line.
“Getting Jai is a major coup for us. He’s a front-rower who can play at loose forward. He is good with the ball and also very tough defensively. I’m sure he will fit in really well and I’m looking forward to having him on board.”
Leigh have yet to win a game on their return to Super League and currently sit at the bottom of the table. The Centurions will attempt to get their first win of 2021 when they host Hull KR on Sunday.