The 27-year-old has been granted a release from the last two years of his Rabbitohs contract opening the way for him to join several fellow Kiwi internationals at Mt Smart Stadium.
It means the Warriors will start 2016 with three of the Kiwis' spine players from the line-up that accounted for the Kangaroos 26-12 in Sunday's Anzac Test at Suncorp Stadium in Brisbane - Tuivasa-Sheck, Luke and halfback Shaun Johnson.
It was Luke's 33rd Test since his Kiwi debut in 2008 while he has also played 176 NRL games for South Sydney so far.
"I've been away from home for a long time now and I really miss it," he said.
"I've loved playing for the Rabbitohs. They've done so much for me but I wanted to go back to New Zealand at some stage and I'm grateful they've allowed me to go.
"Going home to play for the Warriors has always been something I wanted to do. I know so many of the boys there and I also like what's happening at the club since Jim has taken over."
Warriors chief executive Jim Doyle said Luke's signing was one of the most significant in the club's history.
"On top of signing Roger as well, it's a fantastic coup for us to secure Issac," Doyle said.
"We are always looking to bring elite players to our club and in Issac we have signed one of the very best there is."
Warriors head coach Andrew McFadden was elated.
"His arrival at the club will provide a massive lift to our side," he said.
"With the game getting faster and the prospect of the number of interchanges being reduced, 80-minute hookers have become a real asset. Issac is an exceptional dummy half and he underlined that for the Kiwis in the Anzac Test against the Kangaroos. He was outstanding.
"It's hugely exciting for us knowing Issac and Roger will on board next year."
While he missed last year's NRL grand final through suspension, the Hawera-born Luke was a critical contributor to South Sydney's first premiership in 43 years.
He has also been as integral performer in the Kiwis' string of international successes in the last seven years. He was used from the interchange bench in the wins in the Rugby League World Cup final in 2008 and the Four Nations final in 2010 while he started in the Four Nations final win last year and again in Brisbane last Sunday when the Kiwis won their third consecutive Test against the Kangaroos.
- by Daniel Richardson of NZME. News Service
