The Sea Eagles were keen to retain Stewart but salary cap pressures prevented them from formally tabling an offer. The move will raise further questions about whether his brother, star fullback Brett, will attempt to follow him. Brett recently put his northern beaches property up for sale.

It's the second big Stewart story in as many days after Brett was arrested for driving under the influence on Easter Monday.

The Rabbitohs had money to spend following Sam Burgess' decision to switch codes at the end of next season. They have already signed out-of-favour Panther Tim Grant for next year and could also lose Queensland Origin forward Ben Te'o, who has been linked with a return to Queensland.

Several NRL clubs, including the Dragons, were interested in Glenn Stewart's services but the Redfern outfit eventually won out.

The Sea Eagles will have signing news of their own, with utility back Peta Hiku's retention on a three-year deal expected to be announced this week.

Stewart says he is excited about joining the Rabbitohs.

“I’ve really enjoyed the times I’ve had at Manly over the past 12 seasons but circumstances at the club have led to me moving on at the end of this year,” Stewart said in a statement.

“I’m really excited about moving onto that next chapter of my career next year and I’m looking forward to the change, and the challenges, that will come with joining the Rabbitohs,” Stewart said.

“I’m glad to have this sorted out early in the season so that I can now concentrate on finishing off the job I need to do for Manly this year.”

Rabbitohs coach Michael Maguire said: “Glenn is one of the lynch-pins to the extended success the Sea Eagles have had over the past decade and he will bring a lot to our club.”

“Glenn has achieved a lot throughout his time in the game and the experience that he has at the highest levels on the biggest stage, as well as his leadership qualities, will be invaluable to the young players we have coming through in our squad."