After appearing at the post-season test for Alfa Romeo in December 2020, it was announced that Ilott will be taking the role of Scuderia Ferrari test driver for the 2021 season. In April 2021 he was appointed Alfa Romeo's second reserve driver, sharing duties with fellow reserve Robert Kubica. Ilott appeared in FP1 for the team at the and the Austrian Grand Prix, running No. 98.