At the 2008 UEFA U-17 Women's Championship, Popp won her first international title with Germany, scoring the team's second goal in the final. The same year, she reached third-place at the 2008 FIFA U-17 Women's World Cup. In February 2010, Popp made her debut for Germany's senior national team in a friendly match against North Korea. Less than two weeks later she scored her first two international goals at the 2010 Algarve Cup in a 7–0 win over Finland.