Grosjean chose to compete in the IndyCar Series in 2021. He joined the series on a joint deal with Dale Coyne Racing and Rick Ware Racing. Grosjean was scheduled to only participate in the street and road course events in the 2021 season but he later announced after the Indianapolis 500 that he would run the Bommarito Automotive Group 500 to get experience racing on ovals for a potential full schedule in 2022. Because his only oval race would be on what IndyCar considers a short oval Haas F1 Team colleague Pietro Fittipaldi was signed to replace Grosjean for IndyCar's three races on superspeedways, the double header at Texas Motor Speedway and the 2021 Indianapolis 500. Grosjean's signing coincided with the arrival of three time Supercars champion Scott McLaughlin and seven time NASCAR champion Jimmie Johnson to IndyCar, creating what some pundits dubbed the most intriguing rookie class to American Open Wheel Racing since the arrival of Nigel Mansell to CART in the early 1990s. Many pundits picked Grosjean to have the strongest season of the three due to his extensive open wheel experience, picking him to be a potential candidate for IndyCar Rookie of the Year despite competing for a team with significantly less resources than McLaughlin's Team Penske or Johnson's Chip Ganassi Racing and not racing a full schedule. Grosjean however stressed that he faced a significant learning curve adapting to both the Dallara DW12 and the new tracks he was going to race, cautioning F1 fans paying close attention to his performances to have realistic expectations for him to start the series. He uses a helmet designed by his kids, which was originally intended for use during the 2020 Abu Dhabi Grand Prix.