Delap was a talented javelin thrower in his youth, and was touted to represent Ireland in the Olympics after his throw-ins shot to prominence following Stoke's promotion to the Premier League.

In 1997, he was part of the side which gained promotion to Division Two and defeated Colchester United on penalties to win the Football League Trophy at Wembley Stadium.

[8] Later that season, Delap scored and assisted a goal in a 3–0 win over Leicester City – a game in which Stan Collymore broke his leg.

[14] Although Delap failed to score during the 2002–03 campaign, he made a total of 30 appearances in all competitions and helped Southampton reach the 2003 FA Cup Final, despite missing the game due to an ankle injury.

Both goals came in the last ten minutes of the game, and would have secured three points for Southampton had it not been for Robin van Persie's last-minute equaliser, which maintained Arsenal's position at the top of the Premier League.

[25][26] Although the injury sidelined him for the remainder of the 2006–07 season, Stoke manager Tony Pulis signed Delap on a permanent basis on 9 January 2007.

His throws continued to cause further problems for Stoke's opposition throughout the season, and would have earned the Potters a point against Everton on 14 September, had it not been for Tim Cahill's 77th-minute header.

[36] He returned the following week to face Portsmouth, and despite helping to create Ricardo Fuller's goal from a throw-in, Stoke lost the game 2–1.

Although Christophe Berra of Wolverhampton Wanderers attempted to clear the ball, it fell to Matthew Etherington, who volleyed it into the top corner.

Daniel Parslow headed the first into his own net, before Ricardo Fuller put Stoke ahead after York failed to clear the second.

[45] In their fifth-round tie against Manchester City, Fuller converted yet another Delap throw-in to cancel out an early goal from Shaun Wright-Phillips.

Just a few minutes after Klasnić's goal, he received two yellow cards in quick succession, with the second coming after catching Delap in the face while challenging for a header.

They created goals against Brighton & Hove Albion,[54] West Ham[55] and Bolton Wanderers, helping Stoke reach their first ever FA Cup Final.

[60] On 19 February 2012, in the fifth round of the FA Cup against Crawley Town, Delap received a straight red card for a sliding tackle on David Hunt.

[62] Delap made a total of 36 appearances in all competitions, six of which came in Stoke's historic Europa League campaign, which saw them reach the round of 32 before being knocked out by Spanish side Valencia.

[65] Following his debut in a 2–1 win over Blackpool,[66] his throw-in quickly caused problems as it created Scott Golbourne's equaliser in a 3–2 victory over Middlesbrough.

[67] He then assisted Chris Dagnall's header in his third league appearance against Wolves,[68] before his throw created Tomasz Cywka's goal in a 5–3 defeat to Bristol City.

[70] After leaving Stoke, Delap spent time on trial with League Two side Burton Albion in an attempt to earn a contract.

[87] In June 2023, Delap was appointed assistant under head coach Robbie Keane at Israeli club Maccabi Tel Aviv F.C.

[88] Delap and his former international teammate Keane were evacuated to Greece during the Gaza war, while their team led the table with four wins and a draw.

Numerous experts, including his former manager Tony Pulis, commented on the technique Delap employed, the length and flatness undoing many a defence.

"[92] Fellow professionals similarly renowned for long throw-ins, such as Mario Melchiot, formerly of Wigan Athletic, and Lee Dixon, formerly of Arsenal, also spoke of their admiration for Delap.

Delap said he did not work on building his upper body strength and physique, although he used his shoulders and lower back muscles to give power to his throw.

For the ball to reach his target faster, Delap threw it on a flat trajectory releasing in such a way as to cause large amounts of backspin.

The then Chelsea manager Luiz Felipe Scolari described the technique as "fantastic" and suggested the goalkeeper ought not to attempt claiming the ball in this situation.

[97] On 27 March 2010, West Ham United erected an extra set of advertising boards considerably close to the touchline to hamper Delap's run-up, but he was still capable of reaching the penalty box in spite of the limited space.

These boards backfired when West Ham lost possession from a Julien Faubert throw-in, which led to Ricardo Fuller scoring the only goal of the game in Stoke's favour.

Stoke City Football Club have a partnership with the Donna Louise Trust and one Christmas I went with some of the other players and it was like being hit by a sledge hammer.

[104] His uncle is Paddy Delap, a Letterkenny businessman, golfer,[105] and athletics coach who runs Clarke's Newsagent's and organises an annual charity cycling event in aid of cancer noted for launching the career of former Cervélo TestTeam member Philip Deignan.

Delap also took part in and won Marco Pierre White's Stoke Kitchen contest, with the proceeds benefiting Caudwell Children.