The 27-year-old scored 61 tries in 108 NRL games for Auckland-based Warriors and has been capped by New Zealand and Tonga.
He made his NRL debut in 2014 and was the competition’s top try scorer three years ago, with 23 in as many appearances.
Fusitu’a, who had two years remaining on his Warriors contract, will join Rhinos in pre-season, once paperwork has been completed.
“It is going to be something new and fresh,” he said of the move. “Me and my family are excited to come over to England.
“Leeds have been a proud and successful club for a long time and I am looking forward to getting over, meeting the boys and starting the hard work with the team.”
“I spoke to [Rhinos coach] Richard Agar and you can see how genuine he is and the care he has for the club and his players.
“He wants to play an exciting brand of rugby, like the Warriors and I am excited to come over and be part of that.”
He added: “As young kids we play rugby league because, first of all, we love the game.
“For me to come over to the Rhinos, have a smile on my face, train hard and hopefully win plenty of games to give the fans something to cheer about will be special.”
Fusitu’a is only the 24th player to make 100 appearances for Warriors, where he was the longest-serving squad member.
Born in Auckland, he scored two tries in two Tests for the Kiwis five years ago before switching to Tonga, bagging five touchdowns in nine appearances, including a hat-trick in a win over New Zealand at the 2017 World Cup.
Agar said: “We are really excited to have signed David and I think he will be a great addition to our team.
“Undoubtedly, he is a world-class talent – you only need to look at his highlights reel and see the spectacular tries he can score to know he will soon become a crowd favourite at the Rhinos.
“In the modern era, it is rare a player of his ability becomes available for a Super League club and it is a great boost for us to have beaten off competition from a number of clubs to have secured his signature.”
Fusitu’a played in the Warriors’ first five games of 2021 before suffering a hamstring injury. He made his comeback in August, featuring twice for Queensland Cup side Redcliffe Dolphins.
“He is still only 27 and, while we understand the reasons why he has not played as much football as he would have liked last season, having spoken to him, he is keen to return to his best in a Rhinos shirt,” Agar added.
“He is a player who loves to play with a smile on his face and I know he and his young family are looking forward to being part of the Rhinos family.”
Fusitu’a can also play at centre and joins half-backs Aidan Sezer (from Huddersfield Giants) and Blake Austin (Warrington Wolves) and second-rower James Bentley (St Helens) on Rhinos’ list of recruits for next season.
Rhinos squad for next term will include wingers Tom Briscoe, who had a spell in the centres this year, and Ash Handley, but Luke Briscoe, who missed only two games in 2021, has left the club and is set to join Featherstone Rovers.
Rhinos have also been looking for a middle-forward, but Fusitu’a will complete their overseas quota.
Chief executive Gary Hetherington said the signing is “great news for Rhinos fans and for Betfred Super League”.
He insisted: “David is one of rugby league’s most exciting players and will certainly add some speed and class to next season’s Rhinos squad.
“I believe our overseas cohort are the strongest we have had for many years and show the careful management of our group to bring in world-class talent to develop and work alongside our outstanding crop of young players coming through our own development pathway.”