Peter made her debut in the German national team in March 2006 against Finland. She was part of Germany's winning team at the 2007 FIFA Women's World Cup, but did not play in any game. One year later, she won the bronze medal at the 2008 Summer Olympics, where she became a regular starter for Germany in the knockout stage of the tournament. Peter was part of Germany's team winning the country's seventh title at the 2009 European Championship. She scored her first goal for the national team at the Algarve Cup facing China in March 2010. Peter was called up for Germany's 2011 FIFA Women's World Cup squad.