The 24-year-old, who will begin training with the Panthers next week, played 154 games for Leeds after making his debut for the Super League club in 2011.
In 2015 Hardaker was named Man of Steel after helping Leeds win the Challenge Cup, League Leaders Shield and First Utility Super League Grand Final.
"This is truly exciting for the Panthers to have a current English international joining the club for the remainder of the 2016 season," Panthers Executive General Manager Phil Gould AM said.
"Zak is an outstanding footballer. With long term injuries to our Kiwi international centres Dean Whare and Peta Hiku, Zak's arrival at the club is very timely indeed.
"Zak wants to prove himself in the NRL competition and may well consider a longer stint in Australia if all goes well. It will be a fantastic experience for Zak and for the Panthers".
Meanwhile hooker James Segeyaro has been released from the remainder of his contract with the Panthers to immediately link up with Leeds.
"It will be a great experience for James to live and play rugby league in another part of the world and I wish him the very best," Panthers CEO Rugby League Corey Payne said.
Segeyaro played 70 games for the Panthers after joining the club ahead of the 2013 season. In 2014 he was named Dally M Hooker of the Year.
"I want to thank James for his service to the Panthers," coach Anthony Griffin said.
"For the last three and a half seasons he has been a valued member of the club and we wish him all the best for the next chapter in his career."