Karl confirmed his return recently, telling the Sydney Morning Herald that the news has "shocked" him more than anyone.
"I am as shocked about this as everyone else," he told the publication.
"It's not something I thought would ever come up again. I thought my time was up, but then, when I was sounded out about it, it got me thinking. It's a big job with enormous pressures and I know only too well some of those pitfalls, but it is also without question the best live TV job in Australia."
While Karl gets ready for his return as co-host, it's come to light that he's agreed to forfeit a third of his salary package, according to The Daily Telegraph.
Karl’s last contract, negotiated in December 2015 with Nine’s then new CEO Hugh Marks, included a $1 million dollar “image bonus” and part of — or all of which — could be withheld by bosses should he fail to achieve standards expected of him, well-placed sources told the publication.
A Nine insider told the publication on Sunday that bosses likely used this clause to "slash" his contract after he was axed from the Today show in December 2018.
Karl is set to return to the Channel Nine breakfast programme in 2020. While he won't be joined by his original partner in crime Lisa, it appears there's no "bad blood."