The 2015 Man of Steel played 11 games for Penrith last season - 10 of them off the bench – after joining the Panthers midway through the year on loan from Leeds Rhinos.
Hardaker, who scored 67 tries in 155 games for Leeds, managed just one four pointer for the Panthers.
He has signed a one-year loan deal with the Castleford Tigers after NRL clubs baulked at the $525,000 transfer fee Leeds was seeking.
"There is no doubt he is an outstanding rugby league player," Tigers head coach Daryl Powell said.
"His flexibility in playing a number of positions in the backline will clearly enhance what is already a very talented squad and add quality competition."
Meanwhile, the talented Englishman opened up on the personal turmoil that led him to request a transfer to the other side of the world last season.
"I'm in a really good place, so that's why I can't wait to get started," he told BBC Look North.
"Me and my partner at the time we were supposed to have a baby and the crux of it is we didn't, so I took it a bit the wrong way and it was a bit of an upsetting time.
"I pretty much locked myself away and went a few weeks without seeing anybody. It took me a few months before I realised I could talk about it."