Müller made her debut for the German national team against the United States in July 2000. In the following years, she won several major titles with Germany, almost exclusively as a reserve player, often coming on as a late substitute. Müller won her first international trophy at the 2001 European Championship. Two years later, she was part of Germany's winning team at the 2003 FIFA Women's World Cup. She had three appearances and scored twice in the tournament.