The 22-year-old, who currently plays for Super 15 side Cheetahs, will officially arrive at Sixways Stadium in the summer.
"I am delighted that Nick has decided to move to Warriors. He is aware of our long-term focus and is committed to being part of our journey," Worcester director of rugby Dean Ryan told the club's official website.
"Nick is the sort of player who will add to this club and he has the potential to be an outstanding Premiership player so we are looking forward to welcoming him to Sixways."
Worcester return to Aviva Premiership action on Saturday when they travel to Bath.