The popstar - whose latest single Bon Appetit flopped in Australia, debuting at No.35 on the ARIA charts with just around 4000 sales - is the first judge named for the rebooted singing contest, which flips US networks from Fox to ABC for its upcoming revival.

The network was keen to secure a big-name ahead of last week's "upfronts" presentations in New York, leaving Perry with "all the leverage", TMZ reports.

"If ABC ended up announcing the show without a judge, they'd be screwed," a source told the website, citing the network's competition with rival NBC's The Voice.

The hefty paycheque makes Perry the highest-paid judge ever on the series, eclipsing Jennifer Lopez's $US15 million ($20 million) haul during the show's 15th season, which wrapped up on Fox last April.

It also shoots Perry straight into the higher echelons of TV's top-paid stars, on par with The Big Bang Theory's cast, earning her over $US1 million per episode for the season's 24-episode run.

In an interview with The Hollywood Reporter, ABC's reality chief Robert Mills justified the heavy spending.

"What you can't do is come back as bargain-basement Idol," he said.

"We're going to make sure the talent is right, and we'll do what we have to to make it bigger and better than ever."

The network is still attempting to lure longtime host Ryan Seacrest to the series with a similarly sizeable offer.

American Idol was a ratings juggernaut for Fox through its first few seasons, pulling in a staggering 30.75 million viewers on average during its fifth-season apex.

That dropped significantly during the show's final season last year, which averaged just around 9.09 million viewers with a judging panel that included Lopez, Harry Connick Jr and Keith Urban.

The series, produced by Fremantle Media, is due to premiere in the US in early 2018, with a local broadcaster yet to be confirmed.

A spokesperson for Ten, who aired Australian Idol from 2003 to 2009, says the network has "no current plans" to reboot the series here.