The 29-year-old has played for five teams in Australia's NRL, including Wests Tigers and New Zealand Warriors.
Gavet follows full-back Ashton Golding to the Super League side after his move from Leeds Rhinos.
"I hope I can be the piece that fits perfectly to complete the puzzle," Gavet told the Huddersfield website.
Head coach Simon Woolford said: "James had a number of options including some top Super League clubs, so we're thankful to James and his management for making the choice to come to Huddersfield and we feel this is a major coup for the club."
Huddersfield finished 10th last season, just two points above bottom side London Broncos.
Source:
BBC