[3][4] A former Italian international, Pazzini earned a total of 25 caps and represented his nation at the 2010 FIFA World Cup.

Born in Pescia, Pazzini started his career at Atalanta, with whom he made his professional debut in 2003, and quickly emerging as a promising youngster.

As a result of limited first team opportunities, Pazzini agreed a move to Sampdoria in January 2008 for a €9 million transfer fee.

[6][7] After his first match, against Palermo, in the next matchday Pazzini found the back of the net for the first time with the blucerchiati against Udinese in the Coppa Italia.

He combined well with Antonio Cassano up front, forming arguably one of the most effective partnerships of the season in Serie A, and drawing comparisons with Sampdoria's former Gianluca Vialli and Roberto Mancini strike-pairing of the late 1980s and early 1990s.

Pazzini began the 2011–12 season on a weak note, failing to score until the fifth matchday in a 3–1 victory over Bologna.

Pazzini also added another goal later that month against Lecce and scored in Inter's opening match of the 2012 calendar year in a 5–0 victory against Parma.

)[16][17] On 24 August 2012, Pazzini told La Gazzetta dello Sport of what occurred at Inter: "I dream about being a deciding factor in a derby and in many other matches.

Regarding the swap that brought Cassano to Inter, Pazzini stated, "Antonio and I have been friends since our days at Sampdoria.

[23] Upon the expiration of his Milan contract in the summer of 2015, Pazzini moved on a free transfer to Hellas Verona, his sixth professional club.

[23] On 31 January 2018, Pazzini joined Spanish La Liga club Levante on loan for the remainder of the 2017–18 season.

[24] He made his debut on 3 February 2018, coming off the bench in the 77th minute and scored the equalizer in a 2–2 draw against Real Madrid.

[25] On 15 December 2019, at the age of 35, Pazzini scored his first goal in Serie A since 30 October 2017, from the penalty spot, which helped his team to come back from behind and achieve a 3–3 home draw against Torino.

[27] Pazzini made his debut with the senior Italian team on 28 March 2009 in a World Cup qualification match against Montenegro, scoring his first goal.

Pazzini started the friendly against Northern Ireland in Pisa on 6 June 2009, where he missed a penalty in the 55th minute.