|Date of birth||2 July 1989|
|Place of birth||Paderno Dugnano, Italy|
|Height||1.81 m (5 ft 11 in)|
|1993–1995||Oratorio San Luigi|
|1997–2003||Centro Schiaffino Calderara|
|2009–2010||→ Modena (loan)||23||(1)|
|2010–2011||→ Crotone (loan)||20||(2)|
|2011||→ Verona (loan)||2||(0)|
|2012||→ Prato (loan)||5||(1)|
|* Senior club appearances and goals counted for the domestic league only.
Born in Paderno Dugnano, in the province of Milan, Napoli started his career at Pro Sesto of Serie C1. He was signed by Internazionale Primavera in a co-ownership deal in January 2007, for a fee of about €70,000 (in part-player swap: Marco Dalla Costa and Daniele Federici), but was loaned back to Pro Sesto for the second half of the 2006–2007 season. He officially became a player of the Nerazzurri Primavera on 1 July 2007.
He made his first team debut against Reggina Calcio on 19 December 2007. That Coppa Italia match Inter beat Reggina 4–1 and Napoli replaced Hernán Crespo just 1 minute before the 4th goal by Mario Balotelli in the 86th minute. Napoli wore no.46 (of 1st team) in the 2007–08 season. The Primavera League regular season team top-scorer in both 2007–08 and 2008–09 season, Napoli was purchased outright by Inter on 30 January 2009.
In July 2009, along with Primavera team-mate Cristian Daminuţă and Enrico Alfonso, they were loaned to Serie B side Modena. He was awarded a no.11 shirt. He made 23 league appearances, started 12 times for the team which finished in mid-table.
In July 2011 he was sold to Serie B newcomer Juve Stabia in co-ownership deal, joining Cristiano Biraghi. However, on 31 August he returned to Inter without any appearances with Juve Stabia. In January 2012 he joined Prato on loan in Lega Pro Prima Divisione and he scored the decisive goal in the play-off against Piacenza. In July 2012 Prato finally signed him permanently. In July 2013 he signed a two years contract with A.C. Pisa 1909.
- "Samp v Inter: Mancini's Primavera call-ups". inter.it. 23 February 2008. Archived from the original on 26 February 2008. Retrieved 23 February 2008.
- FC Internazionale Milano 2006–07 bilancio, Require purchase in CCIAA (Italian)
- "TRANSFERS: INTER'S JANUARY DEALINGS". inter.it. 31 January 2007. Retrieved 6 June 2010.
- "Tim Cup: Reggina 1–4 Inter". inter.it. 19 December 2007. Retrieved 6 June 2010.
- "Academy ins and outs". inter.it. 2 February 2009. Retrieved 6 June 2010.
- "Three players on loan to Modena". inter.it. 14 July 2009. Retrieved 14 February 2010.