Ilott, 22, finished second in this year’s F2 points to Schumacher, who graduates to F1 as a race driver with Haas F1 in 2021.
Ilott scored five pole positions and three wins with the UNI-Virtuosi team this season. He has been part of the Ferrari Driver Academy since 2017, and was previously a Red Bull Junior driver, but was dropped from its programme after the 2015 season.
“I am very pleased to be joining Scuderia Ferrari as its test driver from next year,” said Illott.
“I look forward to contributing to the work the team does on and off track, and to all of the new things I can learn by taking on this exciting new challenge. I will give my all to do a good job and gain as much experience as possible to continue making progress as a driver.
“I would like to thank the Ferrari Driver Academy and Scuderia Ferrari for this great opportunity and their support. It has been an honour to be part of their programme for the past three years and I am pleased to continue our journey together.”
He has previously tested F1 machinery for Alfa Romeo at Barcelona in 2019, where he crashed, but plans for him to drive in free practice for Haas at the Nurburgring was cancelled due to bad weather conditions.
He then drove a 2018-spec Ferrari at Fiorano in September with fellow academy members Schumacher and Robert Shwartzman, and was back in the Alfa in today’s young driver test in Abu Dhabi.
Earlier this week he confirmed he would not be returning to F2 in 2021, saying “I only missed out [on the title] by 14 points.
“I could always give reasons why, but I don’t want to give excuses. I feel like if you are in the top three or top two, you shouldn’t have to prove yourself again.”
A costly spin in the second of the four Silverstone races while well placed led to a non-finish, while contact in the Mugello feature and Bahrain sprint races allowed Schumacher to stretch his F2 points advantage.
An enforced pitstop for the Prema driver in the Sakhir finale presented an opportunity for Ilott to mount an attack on the top-two place he needed to overhaul his rival in the championship, but the UNI-Virtuosi driver’s overworked tyres meant he was powerless to avoid slipping back to an eventual 10th as a relieved Schumacher claimed the title in 18th.