Ericsson was confirmed for a longer tenure with Chip Ganassi in October 2020, re-upping for at least another two seasons. 2021 would be Ericsson's breakout year in IndyCar. Although he had middling performances compared to teammates Scott Dixon and Alex Palou before the 2021 Indianapolis 500 Ericsson would outscore both his teammates and the entire IndyCar field following the Indianapolis 500. Ericsson scored his first win in IndyCar and his first win in any category since 2013 in GP2 when he won the first race of the double header in Detroit, a race in which Ericsson benefited from the misfortune of race leader Will Power after Power's car refused to restart during a formation lap following a red flag incident at the end of the race. Ericsson finished second to Josef Newgarden at Mid Ohio and picked up a second victory at the chaotic inaugural round at Nashville.