The former Leeds Rhinos and Castleford Tigers academy player has just had a significant role in helping Bradford win promotion to the Championship.
Now Halafihi, who could have carried on at Odsal, wants to help steer Hunslet out of League 1, too, in 2019.
“Vila had the opportunity to stay at Bradford, and other clubs were chasing his signature, but he wants to challenge himself and fulfil his undoubted potential,” said Hunslet coach Gary Thornton.
“I’m really pleased he has decided to join us; we want players with a winning mentality, who knows what it takes to get a team promoted, and he will add that experience to the group.
“I’ve coached him before during his development through the Castleford academy, and he has a real hunger for success, backed up with a very professional attitude to everything he does.
“He is a very skilful and knowledgeable hooker, but is equally effective at centre or back-row, so he gives us added flexibility in other areas if needed.”
Leeds-born Halafihi, 24, has also spent time in Australia where he spent a season with NRL side Penrith Panthers’ Under-20s side.
He scored four tries in 17 appearances for Bradford this term and said: “I’m excited at this new challenge.
“I can’t wait to start pre-season training and meet all the boys. With the quality of recruitment at the club this year I see no reason why we shouldn’t be looking for promotion.
“GT and Darren (Williams) have added some top Championship players to an already talented squad and I can’t wait to get started.”