Kubica joined Alfa Romeo Racing in a reserve driver role for the 2020 season, returning to the team he made his Formula One debut with in (when it was still known as BMW Sauber). He competed at the pre-season test at the Circuit de Barcelona-Catalunya and set the fastest laptime during the fourth day of testing. He was joined by 2019 F2 Championship driver Tatiana Calderón. During the season, Kubica completed tests at the Styrian, Hungarian, Bahrain and Abu Dhabi Grands Prix. He also participated in the season-ending Abu Dhabi Young Drivers Test.