In May 2018, Moon was named in South Korea's preliminary 28 man squad for the 2018 FIFA World Cup in Russia.[99] This was due to his impressive performance at Incheon United at the start of the 2018 season.[100] He made his South Korea’s debut against Honduras on 28 May 2018, coming on as a 56th minutes and scored the national side’s second goal of the game, in a 2–0 win.[101] Moon appeared in the next two matches, both coming on as a substitute.[102] He eventually made to the 23 man squad.[103] After missing two matches due to an injury and saw him placed on the substitute bench, Moon made his World Cup debut against Mexico on 23 June 2018, and played 77 minutes before being substituted, as South Korea lost 2–1.[104] Following the match, Osen gave Moon’s performance a 6.5 points, due to being actively involved in the frontline counterattack situation.[105] He made another World Cup appearance, coming against Germany and played 69 minutes before being substituted, in a 2–0 win on 27 June 2018, but South Korea was eliminated in the Group Stage tournament, finishing third place and made two appearances.[106] Following the tournament, Best Eleven evaluated Moon’s performance, especially against Germany.[107]