On 6 June 2019, Roestbakken was promoted from the standby list to the senior Australia squad for the 2019 World Cup, replacing the injured Laura Alleway. Her U20 manager, Gary van Egmond, also acts as assistant with the senior team and had previously hinted at her chances of making the squad despite being uncapped, praising the teenager's work rate, technique and desire for the game. She made her senior debut as a stoppage time substitute in Australia's second group game of the World Cup, a 3–2 victory over Brazil.