Born and raised in the United States to an Irish father,[4] she initially represented the country of birth at the youth international level before switching to play for the Republic of Ireland senior national team in 2023.
Farrelly was a member of the Spirit United Gaels club that was the 2006 National Runner-Up and was played for the Region I Olympic Development Program (ODP) team.
The Gaels made it through to Regionals the next year on a wildcard after a tough loss to the FC Pennsylvania Strikers in the State Cup Final.
[citation needed] Farrelly attended the University of Virginia and played for the Cavaliers in the Atlantic Coast Conference (ACC).
During her senior year, Farrelly was honored as the University of Virginia's top female athlete of 2010–11 after starting all 22 games and leading the Cavaliers with 12 goals and seven assists (for a total of 31 points).
[10] Farrelly's 90 games started ranks her second to future FC Kansas City teammate, Becky Sauerbrunn in the school's history.
[15] In 2013, Farrelly signed with FC Kansas City for the inaugural season of the National Women's Soccer League.
[16] She scored her first goal for the club in a home match against Seattle Reign FC, helping the Blues notch their first win for the season.
[19] On 26 October 2015, Boston Breakers announced that they had obtained Farrelly from Portland Thorns FC in a package deal along with McCall Zerboni for first-round (No.
[21] In October 2016, Seattle Reign FC selected Farrelly off the NWSL Re-Entry Wire after the Breakers waived her at the end of the 2016 season.
Her former college coach Steve Swanson connected Farrelly to NJ/NY Gotham FC general manager Yael Averbuch West, who arranged a tryout.
[27] On 25 March 2023, over six years after her retirement from professional soccer, Farrelly signed for NJ/NY Gotham FC on a one-year contract with an option for 2024.
[35] During her career, Farrelly was closely connected to former women's soccer coach Paul Riley, playing for three of his teams in three different leagues.