In May 2019, Gielnik was named to her first World Cup team. At the World Cup Gielnik appeared in three matches for Australia, starting two of them. In the Round of 16 against Norway, she entered the match as a second-half substitute replacing Hayley Raso. With the match tied 1–1 after extra-time, the game went to penalties. Gielnik was the second penalty taker for Australia, she had her penalty saved. Australia lost to Norway 4–1 on penalties and were eliminated from the World Cup.