In June 2000, Udinese completed the signing of the young prospect and in his first season with the club, Iaquinta made 16 appearances and scored two goals.

That following season, Iaquinta made 34 appearances with 17 goals, including a hat-trick in his first UEFA Champions League group stage match against Panathinaikos.

During the 2007–08 season, Iaquinta made only a handful of starts for Juventus, mostly being used as back-up to the experienced strike partners Alessandro Del Piero and David Trezeguet, who combined to score 41 goals between them in the Serie A alone.

[7] Iaquinta started the season as fourth-choice striker, but enjoyed a particularly impressive string of performances when both Amauri and Trezeguet were injured, gaining a more regular place under Claudio Ranieri.

After that, Iaquinta also played regularly in Serie A games, his situation helped by a falling-out between Trezeguet and head coach Claudio Ranieri.

Following the sacking of Ranieri, and the appointment of Ciro Ferrara for the 2009–10 season, Iaquinta became an undisputed starter, before a major injury side-lined him for six months between October 2009 and March 2010.

[9] He made his debut for them on 9 February away at Lazio, and assisted Adrian Mutu for the first goal and scored a penalty to put Cesena 2–0 up at half-time, but they eventually lost 3–2.

[8][14][15] Iaquinta made his international debut for Italy on 30 March 2005, as a half-time substitute for Luca Toni in a 0–0 home friendly draw against Iceland at the Stadio Euganeo in Padua.

[20] He played in 5 out of 7 of Italy's matches, including the victorious semi-final against hosts Germany and final against France on 9 July, in which he came on after 61 minutes for Simone Perrotta.

[17] In his prime, Iaquinta was a tall, physically strong, opportunistic and extremely fast striker, who excelled in the air and at finishing off chances inside the penalty area.

[27][28][29][30][31] Due to his great pace, athleticism, work-rate, tenacity and good movement off the ball, he was also known for his ability to make attacking runs to beat the defensive line and either get on the end of his teammates' passes or provide depth and create space for his team; his speed and timing also made him a dangerous offensive threat on counter-attacks.

[41] On 21 December 2015, they were both sent to trial for the illegal possession of firearms, aggravated by the aiding of the Calabrian Mafia organization 'Ndrangheta expand to Northern Italy, of which his father was charged with association with the 'Ndrangheta through the 'Ndrina of Nicolino Grande Aracri.