The 23-year-old England international should now remain at the club until at least the end of the 2019 season.
“I am really pleased to have signed the new deal,” he said.
I would like to say thank you to Gary Hetherington for the faith he has shown in me and also the club’s supporters, especially our members who every year show their support for the team, and certainly were a big part in why I have committed my future to the club.
“Over the last decade, the fans have been used to a team that grew up together with Kevin Sinfield, Danny McGuire, Rob Burrow and Jamie Jones-Buchanan but obviously things are going to change over the next few years, but there is a group of young players here now who want to follow in their footsteps and make our own history here with the Rhinos.
“It is a really exciting time to be at the club and I am looking forward to the future and achieving more success over the years ahead.”
Leeds coach Brian McDermott was pleased that such an exciting talent was staying put in Super League.
“I am really pleased for Zak himself that he has agreed this new contract and committed his future to the club and our competition,” he said.
“Zak has had some well publicised ups and downs in his career but there is no doubting his ability on the field.
“His work ethic and commitment on and off the field this season can not be questioned and I think over the next few years he will mature into a world class player.
“Our members and the fanbase are a huge part of that, the support the players get creates a bond between the players and the club, a bond that is very hard to break and makes staying at this club a great option for all our players.”