The 28-year-old has been granted an early release by the Warriors after two stints with the club, first making his debut in 2014.
“We thank Agnatius for all he has given the club over the last three years,” Warriors recruitment manager Peter O’Sullivan said.
“He has a great opportunity to take his family to England and we wish them all the best for the future.”
Paasi played just one game with New Zealand before moving to the Titans, where he played 54 games before moving back across the Tasman in 2018.
The Tongan international was riddled with injuries in 2020 and cut his season short to return to Auckland for family reasons.