Youth Gaillard was part of the squad that represented Switzerland at
2013 UEFA Women's Under-17 Championship qualification when she played six matches and scored two goals. With the U19 team, Gaillard played in the
2015 UEFA Women's Under-19 Championship qualification and the
2016 UEFA Women's Under-19 Championship qualification. In the 2016 edition, Switzerland was able to qualify for the
final tournament reaching the semi-finals when they were defeated by
France, that would eventually win the tournament.
Senior In 2015, Gaillard was called for Swiss Senior Team for the first time. In 2016, she made her debut for the team. On 23 October 2016, in a friendly match against
United States, she scored her first international goal. On 3 July 2017 Gaillard was called by coach
Martina Voss-Tecklenburg to represent Switzerland at the
UEFA Women's Euro 2017, but she didn't play any matches as Switzerland was eliminated in the tournament's group stage. In 2022, she took part in the Euros in England with another defeat in the group stage and a year later she was selected as part of the final squad that went to Australia and New Zealand to play in the 2023 World Cup. Switzerland made it to the last 16, where they lost to the eventual champion Spain. On 23 June 2025, Gaillard was called up to the Switzerland squad for the
UEFA Women's Euro 2025. ==International goals==