Born in Torre del Greco, Campania, Esposito made his professional debut in 1997 with Pescara Calcio after having a trial with English club Everton.

After an unsuccessful trial with Rangers, he joined Udinese Calcio with which he first appeared in Serie A, playing just nine league games in two years and also being loaned to his previous club.

In 2001–02, Esposito moved to Cagliari Calcio in the second division, being an undisputed starter during his spell with the Sardinians and scoring in double digits in three of his six seasons – in 2003–04, he netted a career-best 17 goals in 40 matches, with his team finishing in second position and returning to the top flight after a five-year absence.

After his scoring partner David Suazo's confirmed departure, on 4 July 2007, A.S. Roma acquired 50% of Esposito's rights for €2 million, plus the free loan of Daniele Magliocchetti.

On 9 October 2004, Esposito made his debut for Italy, in a 2006 FIFA World Cup qualifier against Slovenia, starting in the 0–1 loss in Celje.