The Briton will join Norman Nato and Will Stevens in Jota's #12 Porsche 963 as the Hertz-backed operation expands to two Hypercar entries. Jenson Button, the 2009 Formula 1 world champion, will join the #38 crew alongside Phil Hanson and Oliver Rasmussen.
Speaking on stage at the Autosport International Show on Saturday, Ilott admitted he had been expecting to remain with Juncos-Hollinger for a third full season with the squad he joined for the final three rounds of the 2021 campaign, but welcomed the chance to revisit a sportscar career that began promisingly in Ferrari GT machinery the same year.
Juncos-Hollinger announced in October that Ilott would split from the team and revealed its signing of Romain Grosjean a few days later, but Ilott revealed that a deal had been done quickly after the final round of the 2023 WEC in Bahrain.
"It’s honestly quite a great surprise," said Ilott, who was joined on stage by Jota team boss Sam Hignett.
"I was expecting to stay in IndyCar, that was the original plan, and circumstances changed as they sometimes do in life.
"We’d reached out to Sam to see what was going on, what the situation was and straight away, I think you were quite keen.
"You had to go to Bahrain to do the final race and have a couple of discussions about what their plan was in general.
"And straight after Bahrain I got word back that we should have a discussion and I think from there it was pretty plain sailing and we moved forward quickly.
"I’m really thankful for it and to be fair it’s a beautiful car in a beautiful championship and I think we have a lot of potential to do a great job."
Hignett said Jota had assumed Ilott "would go to Ferrari with the factory team" in Hypercar before he made the switch to IndyCar, but had kept tabs on him during the intervening years.
"When the opportunity came up to speak to Callum and we had a seat open up in what is now going to be the #12 car, it made complete sense to give Callum a call and see if we could get a deal done," he said.
"I have to say hats off to Callum and your management, it’s the easiest deal I’ve ever done."
Ilott has already driven the 963 in Qatar, which will open the 2024 WEC calendar on 2 March, and remarked that he was impressed by its versatility and complexity.
"I had a little go in Qatar about a month or two ago and what a beast," he said.
"It’s almost like an all-terrain, on-track vehicle, you can just go over anything you like. To a limit!
"Compared to what I’m used to, it’s so versatile.
"Quite tough to drive in a way because it’s quite heavy, but with the hybrid unit, the power, it’s beautiful.
"It’s complex, a bit like the F1 in the way that it’s re-genning and deploying and what you’ve got to manage as a driver, but it’s an amazing car to get into."
