Kopua has been a member of the New Zealand national netball team since 2004, making her on-court debut in 2005 against Barbados. She also played in the New Zealand U21 netball team that won gold at the 2005 World Youth Netball Championships in Florida. During her career she has won gold medals at the 2006 and 2010 Commonwealth Games and the 2009 World Netball Series, and silver medals at the 2007 and 2011 World Netball Championships. In 2008, she co-captained the team with Laura Langman, stepping into the role of acting captain later that year following an injury to Julie Seymour. In July 2009, Kopua became the 23rd captain of the Silver Ferns, taking over from Seymour who retired from the game.