Plattenhardt was first called up to the senior national team in 2017, for the friendly against Denmark on 6 June 2017, for the 2018 World Cup qualification match against San Marino on 10 June 2017 and for the 2017 Confederations Cup to be held from 17 June to 2 July 2017, making his debut in a friendly match against Denmark on 6 June 2017. Plattenhardt was named in Germany's final 23-man squad for the 2018 FIFA World Cup by Germany manager Joachim Löw on 4 June 2018. On 17 June, he made his World Cup debut during their 1–0 defeat in the opening match against Mexico and played for 78 minutes as he was replaced by Mario Gómez in 79th minute.