Deaspite leaving UCD at the end of the season, O'Connor still moved up to the League of Ireland Premier Division signing for Cork City ahead of the 2019 season.[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. Whether it was on the right or on the left, he went and played in behind the striker. He was the one that stood out.'[11][12][13] On 6 October 2020, it was announced that he had left the club, just 5 games before the end of the season after being told he was surplus to requirements by manager Neale Fenn.[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.'[18][19] He scored 5 goals in 47 appearances over his 2 seasons at the club.[7]
Cliftonville
O'Connor signed for NIFL Premiership side Cliftonville on 21 October 2020 until the end of the season.[20][21] In March 2021, Cliftonville manager Paddy McLaughlin called O'Connor 'unplayable' and backed him for a big future in the game.[22] He scored 8 goals in 39 games for the club over the season.[7]
Ayr United
On 28 July 2021, O'Connor signed for Scottish Championship side Ayr United.[23][24] He made his debut for the club on 2 August 2021 in a 2–0 loss to Kilmarnock at Rugby Park.[25] O'Connor scored his first goal for the club on 14 September 2021, opening the scoring in a 3–0 Scottish Challenge Cup win away to Rangers B.[26] He spent 2 seasons at the club, making a total of 59 appearances in all competitions, scoring twice.
Glentoran
On 24 June 2023, O'Connor signed for NIFL Premiership club Glentoran.[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.[28] O'Connor scored 13 goals in 45 appearances in all competitions during his season with the club, as they came 5th in the league.[29]