From 2003 to 2009 Vaillancourt played 88 international games for Team Canada and scored 36 goals adding 39 assists.

While playing for Harvard University she was named the Ivy League and ECAC Hockey Player of the Year.

She made the national team when she was 18 and one of her favourite hockey moments is winning gold on home soil at the Vancouver 2010 Olympic Games.

She was a star for the Harvard Crimson women's ice hockey program and won the Patty Kazmaier Award in 2008.

In her first game ever, she led Canada with 6 points in a 13–0 win over the Kazakhstani national women's ice hockey team.