Former New Zealand international Tui Lolohea has become Kevin Sinfield's first signing for Leeds.
The 23-year-old Wests Tigers stand-off, who played for Tonga in the 2017 World Cup, will join the Rhinos on a three-year deal from 2019.
Leeds say they have been in discussions with Lolohea for a number of weeks but clinched his signing after the appointment of Sinfield as their new director of rugby.
Sinfield said, "We are delighted to have captured a player of the quality of Tui for next season.
"It is rare in the modern game for any Super League club to sign an international-class 23-year-old from the NRL and I am sure he will be a popular addition to our squad."
Lolohea was part of the New Zealand squad who played the Rhinos at Headingley before the three-match Test series against England in 2015 and he says the memory of that match was a factor behind his decision to join the club.
"I have always remembered that game," he said. "The singing and support for the Leeds boys was amazing and I can't wait to play for those supporters.
"That game was Kylie Leuluai's farewell game for the club and I remember the warmth and passion the supporters had for him and the team, that was special.
"People talk about the passion that the English fans have for the game but I had seen it for myself and it was definitely a factor when I was thinking about who to sign for."
Lolohea, who began his NRL career with New Zealand Warriors, was Wests Tigers' top points scorer last season but has been restricted to just six appearances this season due to injury and loss of form.
He added: "I am really excited, it is a long way from home but a different challenge for me and something I am looking forward to.
"It will be very different for me and a new way of life. I am still really young and this is a big journey for me and I want to make the most of my career and my time in England.
"I have had a couple of injuries this year that have held me back at bit but I am looking forward to finishing the season strongly with the Tigers and then making the most of the opportunity to come over to Super League.
"I have seen Kevin play for a number of years and admired him. The professional level that he brought to his whole playing career is going to be massive for the whole team. I am looking forward to being part of his team."
Lolohea will be a replacement for Joel Moon, who is out of contract this year and expected to return to the NRL.