Palmer, who is in the final year of his current contract with Fremantle, has been continually linked with the Giants this pre-season, and it was rumoured this week that he had already signed a four-year deal with coach Kevin Sheedy's side.
Fremantle has denied the reports and Palmer, through his manager Colin Young, labelled them a "joke".
Young, speaking on afl.com.au's Footy Feast radio program, said the rumours were "simply not true".
"He certainly hasn't signed to GWS and I certainly haven't signed him to GWS," Young said.
"It'd be ridiculous for Rhys to sit down with Fremantle or have GWS put down one of those monster offers that everyone's talking about, because he needs to put the score on the board early this season - in the first eight to 10 games - to get his worth back up in the AFL."
Palmer, the 2008 NAB AFL Rising Star, has shown promise this pre-season as he seeks a more permanent return to the Fremantle midfield.
The 22-year-old struggled to regain his best form last year after undergoing a full knee reconstruction in 2009, and he was an emergency for the club's final three games, including two finals.
"He didn't have a great year last year, it wasn't stellar for him coming back from the knee, which does hamper a lot of players," Young said.
The No.7 draft pick at the 2007 NAB AFL Draft was the early standout in Fremantle's pre-season and coach Mark Harvey has trialled him briefly in half-back roles.
Rhys Palmer is a $309,500 midfielder in the Toyota AFL Dream Team competition
