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 draw. 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.