In 2010 she represented New Zealand at the 2010 Fédération internationale de football association U-20 Women"s World Cup in Germany, appearing in all three group games. Armstrong"s family is well represented in international football. Her grandfather father Ken Armstrong was a dual international representing both England and New Zealand.
Armstrong attended Long Bay College.
Armstrong also represented New Zealand at the 2008 Fédération internationale de football association U-20 Women"s World Cup in Chile, again playing all three group games. A 2–3 loss to Nigeria, a 4–3 win over hosts Chile, and scored New Zealand"s goal against England before England equalised late in injury time to eliminate New Zealand from the tournament. Armstrong made her senior international debut as a substitute in a friendly against Japan on 14 November 2009, and scored her first international goal in a 7–0 win over Tahiti on 3 October 2010.
She was a member of the New Zealand squad in the inaugural Fédération internationale de football association U-17 Women"s World Cup, playing all three group games. A 0–1 loss to Canada, a 1–2 loss to Denmark, and a 1–3 loss to Colombia.
