Having competed for another several seasons as an amateur, Delaney reached the final of a Challenge Tour event in 2003, defeating Paul McPhillips and Joe Jogia alongside five others, before losing 3–6 to Lee Spick.

This performance was not enough for him to re-qualify, but the following season heralded runs to the last 16 at another Challenge Tour event – losing 1–5 to Cypriot Mehmet Husnu – and the fifth qualifying round at the 2003 World Championship, where Gary Hardiman beat him 5–3.

The 2007 Welsh Open, in which Higginson would reach the final as an amateur, heralded a 5–3 victory over Spick and a 5–4 defeat of Marcus Campbell, but Delaney lost in the last 48, 0–5 to Stuart Bingham.

At the 2007 World Championship, Delaney defeated Ian Preece 10–7, having trailed 1–5, Barry Pinches 10–9 from 6–9 behind, and Alan McManus by the same scoreline to reach the main stages at the Crucible Theatre for the first time in his career.

With the introduction of Players Tour Championship events in 2010, Delaney played in fourteen tournaments that season, notably beating Patrick Einsle, Rory McLeod, Greene and Li Yan before exiting at the last-32 stage at the 2010 Shanghai Masters, 3–5 to Mark King.