In 2021, Ticktum switched to Carlin alongside Daruvala. In the first round at the Bahrain International Circuit, Ticktum qualified fourth for Sunday's feature race. In sprint race 1 he collided with Richard Verschoor and received a five-second penalty. Despite this, he fought back to finish in eighth place. For the next race, he started from third but was forced to retire after being spun around at the first corner by Robert Shwartzman. In the feature race, Ticktum fell back at the start, but through the use of an alternative strategy, he got back to the lead pack and fought for the race win. When he overtook Oscar Piastri, the Australian collided with him and spun out; Ticktum, however, managed to keep going. He overtook Richard Verschoor on the penultimate lap and finished the race in second, only half a second behind Guanyu Zhou. At the next round Ticktum qualified fourth and finished sixth in the first sprint race in Monaco, and after jumping Théo Pourchaire at the start and overtaking Oscar Piastri into the nouvelle chicane in sprint race two, he ended up second, just behind Liam Lawson. After the race Lawson was disqualified for using an illegal throttle map on the formation lap, which promoted Ticktum to take his first win of the season. In the feature race he battled his rival Piastri for a podium spot, but Ticktum was forced to retire when he got stuck at La Rascasse, after an attempted overtake on the Australian. Following the race Ticktum took the blame for the incident and apologised to his team.
