In May 2017, O'Neill joined Swedish
Elitettan club
Husqvarna FF, scoring two goals in her first match. After two months, she had to return to Canada due to visa issues. In February 2018, she moved to
Roma CF to play in the Italian
Serie B. In September 2018, she signed with
Pink Bari in the
Serie A. In August 2019, she briefly played with Croatian club
ŽNK Split at the
2019–20 UEFA Women's Champions League. In September 2019, O'Neill signed with French
Division 1 Féminine club
Fleury. In January 2020, she joined
Scottish Women's Premier League club
Rangers. In 2021, she returned to play for Split again. In September 2022, she joined German club
Turbine Potsdam. In July 2023, she announced she was taking a step away from the game for a period for her mental health due to the toxic nature of women's football. In August 2023, she signed with English club
London City Lionesses in the second tier
Women's Championship. In December 2023, she took another break from the game due to her pregnancy, missing the remainder of the season. In December 2024, O'Neill joined
Calgary Wild ahead of the inaugural
Northern Super League season. On April 16, 2025, she started in the league's inaugural game, a 1–0 loss to
Vancouver Rise FC. ==International career==