Fox Sports reported that the Broncos announced on Wednesday they had agreed to cut Roberts’ contract short after he requested a release on compassionate grounds.
Roberts has signed a contract with the Rabbitohs which runs to the end of 2021.
“I’m really excited to be coming back to Souths and playing under Wayne again,” Roberts said.
“There are some great players at this club and I can’t wait to get into training and getting back on the field.
“I want to thank the Broncos for everything they’ve done for me and my family over the past four years, but it’s time to move on and to be coming back to the club that I consider to be home is really special.
“I know what it means to the Members, fans and the community to represent South Sydney.
“Now I can’t wait to pull on that red and green jersey and play for the members and the fans of the Rabbitohs.”
He was dropped from the Brisbane side three weeks ago and has been playing reserve grade.
It’s been rumoured he fell out with new Broncos coach Anthony Seibold, and a move south to Sydney will reunite him with Wayne Bennett at Redfern.
“James is a South Sydney junior who knows what it means to represent the Rabbitohs,” Rabbitohs football boss Shane Richardson said.
“Make no bones about it, James is an immense talent, a player capable of representing his state and country under the right guidance, and we feel that James can return to his best football under Wayne and the senior players we have here at this club.
“He will add great strike to our backline and through our discussions with him, we know he wants to return to South Sydney for the right reasons, and he wants to help deliver this club its 22nd premiership.”
Now 26 years old, Roberts’ career began at South Sydney in 2011 but he was axed by the club after 10 games. He went to Penrith for a season and then landed at the Gold Coast where he played 36 games.
Roberts made his State of Origin debut for NSW last year in a winning series, but wasn’t recalled this year after some average form for Brisbane and being dropped to reserve grade.