Slongo also appeared for Switzerland at three IIHF Women's World Championships. Her first appearance came in 2007 IIHF Women's World Championship, where she allowed one goals in nine minutes of playing time. She played in two games at the 2009 IIHF Women's World Championship, winning them both. She also played once at the 2013 IIHF Women's World Championship. She was on the roster for the 2008, 2011 and 2012 championships without playing any games, winning a bronze medal as the #3 goalie in 2012.