She previously practiced as a barrister specialising in criminal law.
O'Connor was educated at Trinity College Dublin and the King's Inns.
[11][12] She was initially not assigned to a circuit and heard cases in Galway.
[2][15][16] O'Connor was the presiding judge in the criminal trials of Tom Humphries in 2017 and David Drumm in 2018.
[19] The Irish government agreed to nominate her to become a judge of the High Court in November 2021.