Upon his return to Arsenal in 2020, Saliba was handed the number 4 shirt. His first appearance for Arsenal was in a pre-season friendly match against MK Dons on 25 August 2020. He was also an unused substitute in the 2020 FA Community Shield, which Arsenal clinched a 5-4 victory over Liverpool in the penalty shootout after the match was 1–1 after 90 minutes. However, he was then left out of the club's competitive squads for the 2020–21 season, leaving him only able to play for Arsenal U23s, with manager Mikel Arteta expressing "regret [over] the decision" before a January six-month loan move to France.