The former Kangaroos forward has inked a two-year deal with Trinity, joining from Cronulla Sharks.
The 31-year-old is no relation to Bill Tupou, who also joined the Wildcats recently.
“It came down to a decision between staying at the Sharks and coming here. I’m really pleased to be here,” he told BBC Radio Leeds.
“I’ve always been a fan of watching Super League games because it’s an exciting league.
“Brian Smith coached my brother at Newcastle Knights and he said how good he was and I’ve only heard positive things from other people too.
“I feel refreshed and I’m looking forward to a new start. I’m not coming over for a holiday, I’ll be ripping in.”