[3] Christiansen has been a member of the senior Danish national team since 2009;[4] making her debut in a 2–0 defeat to the United States at the Algarve Cup and being named in the squad for UEFA Women's Euro 2009.

[6] Christiansen made her international debut for Denmark in the 2009 Algarve Cup against United States on 4 March 2009.

Later on, she was named in national coach Kenneth Heiner-Møller's Denmark squad for UEFA Women's Euro 2013.

Christiansen has been diagnosed with diabetes but states it has not affected her football.

This biographical article related to women's association football in Denmark is a stub.