Petersen was a member of the Germany U19, scoring a goal against Russia during the UEFA U-19 European Championship and the Germany U20, before being called up on 6 August 2009 for the German U21.

Petersen was part of Germany Olympic Squad for Rio's Olympic along with Lars and Sven Bender as one of three allowed players over the age of 23.
On 4 August 2016, he came on as a substitute in the 84th minute for Davie Selke in a 2–2.
Three days later, in the 83rd minute, he was again substituted on for Selke.
On 10 August 2016, he started and scored five goals in a 10–0 win against Fiji.
On 13 August 2016, against Portugal, he again replaced Selke, in the 78th minute.
On 17 August 2016, in the semi-final against Nigeria, Petersen came on for Max Meyer in the 84th minute and scored his sixth goal of the tournament five minutes later.
On 20 August 2016, Petersen entered the pitch as a 76th-minute substitute for Selke in the Gold medal match.
He was the only player who failed to score in the shootout in the Gold medal match and Germany won the silver medal.

On 15 May 2018, he was named in Germany's provisional 2018 FIFA World Cup squad.
Petersen was then handed his first cap in a friendly versus Austria on 2 June in preparation for the World Cup, but was left off of Löw's final squad for the tournament.
Petersen was a member of the Germany U19, scoring a goal against Russia during the UEFA U-19 European Championship and the Germany U20, before being called up on 6 August 2009 for the German U21.
Petersen was part of Germany Olympic Squad for Rio's Olympic along with Lars and Sven Bender as one of three allowed players over the age of 23. On 4 August 2016, he came on as a substitute in the 84th minute for Davie Selke in a 2–2. Three days later, in the 83rd minute, he was again substituted on for Selke. On 10 August 2016, he started and scored five goals in a 10–0 win against Fiji. On 13 August 2016, against Portugal, he again replaced Selke, in the 78th minute. On 17 August 2016, in the semi-final against Nigeria, Petersen came on for Max Meyer in the 84th minute and scored his sixth goal of the tournament five minutes later. On 20 August 2016, Petersen entered the pitch as a 76th-minute substitute for Selke in the Gold medal match. He was the only player who failed to score in the shootout in the Gold medal match and Germany won the silver medal.
On 15 May 2018, he was named in Germany's provisional 2018 FIFA World Cup squad. Petersen was then handed his first cap in a friendly versus Austria on 2 June in preparation for the World Cup, but was left off of Löw's final squad for the tournament.
Nils Petersen