[2] He made his first team debut for the club on 7 March 2015, the opening day of the 2015 League of Ireland First Division season, replacing Dylan Watts in the 89th minute of a 3–0 win over Cobh Ramblers at St Colman's Park.
[4] He was part of the side that won the 2018 League of Ireland First Division title, which was confirmed with a 1–1 draw against Finn Harps at the UCD Bowl on 14 September 2018.
[9][10] He made his Premier Division debut in the opening game of the season away to St Patrick's Athletic as his side lost 1–0 at Richmond Park but he did enough to impress the watching Republic of Ireland manager Mick McCarthy who said 'Daire O'Connor, he was the one player who stood out for me, he played very very well I thought.
[14][15][16][17] In the days the announcement, O'Connor revealed that he was 'baffled' at being told he was no longer required at the club following no falling out with his manager, stating 'I didn't expect to go in Monday morning to training and not go back again.
[27] He made his debut for the club on 13 July 2023, scoring his first career European goal in a 2–2 draw away to Gżira United of Malta in a UEFA Europa Conference League tie.