From Cahir, County Tipperary in Ireland, McCarthy began playing Gaelic football from the age of seven.
[2] She also played camogie, captaining her club Cahir to victory in the 2016 All-Ireland intermediate finals.
In 2017, she was the player of the match in Tipperary's victory in the All-Ireland Intermediate Ladies' Football Championship, scoring one goal and four points.
[4] In September 2018, she was among 18 international prospects to attend the CrossCoders program, a week-long Australian football camp held in Melbourne.
[12] Round four of the 2024 AFLW season saw McCarthy kick a goal after the siren to win the match against the Melbourne Demons at Fremantle Oval.