A full international since 2010, Son has represented South Korea at the 2014 and 2018 FIFA World Cups and is his country's highest scorer in the World Cup jointly with Park Ji-sung and Ahn Jung-hwan with three goals. Son has also represented South Korea at the 2018 Asian Games, where the team won gold, as well as the 2011, 2015 and 2019 editions of the AFC Asian Cup. Korea was runner-up in 2015.