He struck 2–2 in an All-Ireland semi-final defeat to Mayo that year, before he committed fully to the association code of football.

Delaney scored in the final of Cork's winning 2000 FAI Youth Cup side [7] and was promoted to the senior squad for the upcoming 2000–01 League of Ireland Premier Division season under Derek Mountfield.

[12] After a rocky start to his career at Hull, during which time he was tried in midfield and at left-back, Delaney was played regularly at centre back and began to grow in stature and consistency.

In the 2005–06 season in the Championship, he played mainly at centre back, but also at left-back when two players in that position were injured, and in midfield when the manager felt that more height and solidity were required.

Delaney was the last Hull City player to score a goal at their old ground Boothferry Park, prior to their move to the KC Stadium.

Due to Delaney's impressive start to his Palace career, he signed a new contract on 22 November 2012, which expired summer 2014.

[18] He scored his first ever goal in the Premier League in a 3–3 draw against Liverpool, with his initial 25-yard shot deflected slightly into the net by Glen Johnson.

After the end of the 2017–18 Premier League season, Cork City announced that Delaney had signed with the club, and returned on 1 July 2018 after his contract with Palace expired and the Irish transfer window opened.

His first League of Ireland goal came against Derry in his first month back [20] At the start of 2019, Delaney signed for Waterford for the 2019 season.