Sønstevold went through several Norwegian youth teams and participated with the U-17 team in the qualification and the finals of the 2009 UEFA Women's Under-17 Championship in Nyon, where Norway finish in the fourth place. A year later she was part of the team that played at 2010 UEFA Women's Under-17 Championship, but failed to reach the finals. In 2011, she was in the team that qualified and reached the final of the 2011 UEFA Women's Under-19 Championship, when the team finish second after a massive lose for Germany, 8:1. For reaching the semi-finals, the Norwegians had already qualified for the 2012 FIFA U-20 Women's World Cup in Japan. Sønstevold was part of the squad that played the tournament. Norway reached the quarter-finals, but again they weredefeated by Germany, 4:0. On 14 January 2014, she got her first senior international cap against Spain in La Manga, Spain. One year later, she was called for the 2015 Algarve Cup. On 23 April 2015 she was appointed to the provisional squad of 35 players for the 2015 FIFA Women's World Cup. She was initially dropped from the final squad on 14 May, but she was later called into the 23-player roster to replace Caroline Graham Hansen, who had to withdraw to an injury.