In July 2013, Osako was selected the Japan national team for 2013 East Asian Cup. At this tournament, he debuted against China on July 21. In 2014, he was also selected Japan for 2014 World Cup. From 2017, he became a regular player instead Shinji Okazaki. In 2018, he participated 2018 World Cup. He played all 4 matches and scored 1 goal. In 2019, he also participated 2019 Asian Cup. He played 4 matches and scored 4 goals, and Japan won the 2nd place.