Larsson was named in Sweden's 23-man squad for the 2018 FIFA World Cup in Russia. In the last warm-up match before the tournament, a goalless draw with Peru on 9 June, he made his 100th senior appearance for his country. At the 2018 World Cup, Larsson played in four games for Sweden as they were eliminated by England in the quarter-finals. He got his ninth international goal on 28 March 2021, scoring from the penalty spot in a 3–0 World Cup qualifying win over Kosovo.