“It was a hard decision but I’m pleased to have the next stage of my career sorted,” he said.
Rapira, who has only played senior rugby for the Warriors, has played 169 games in his only club’s colours in the NRL.
Warriors head coach Andrew McFadden added: “Sam is a terrific person and a fantastic team man who encompasses all the values we seek in our players.
“It’s a tough day for everyone here and especially his team-mates. We all want this last year to be the best it can be for Sam. He certainly deserves it after the effort he has put in.”