Troianiello started his career at regional league
Eccellenza. He then followed
Calangianus which was
promoted to Serie D. After helping them finish in seventh place, he was signed by
Ischia of Eccellenza. In the summer of 2004, he was signed by
Nuorese, where he helped bring the club from Eccellenza to
Serie C2 in two years. In the 2006–07 season, Nuorese finished as a losing side of promotion playoffs. In January 2007, he was signed by
Frosinone, effective on 1 July.
Frosinone On 1 July 2007, Troianiello became a player for
Frosinone. On 10 July,
Serie A side
Chievo also acquired half of the registration rights for €180,000 (paid via the transfer of
Alfredo Cariello; Troianiello at first joined Chievo in definitive deal and was sold back to Frosinone in co-ownership). He made only five appearances in his first Serie B season, and was loaned to
Ternana of
Serie C1 in January 2008. In the 2008–09 season, he was loaned to
Foggia of
Lega Pro Prima Divisione (ex-Serie C1). In June 2009, Frosinone bought Troianiello outright for €265,000, and
Angelo Antonazzo was bought back by Chievo also for €265,000, Troianiello scored 11 league goals and started 39 Serie B matches for Frosinone in the 2009–10 season.
Siena On 24 June 2010, Frosinone bought his teammate
Caetano outright from Siena, and sold Troianiello to Siena for €2 million. As part of the deal, Frosinone also signed
Gianluca Sansone from Siena in a
co-ownership deal for €400,000.
Sassuolo In June 2012, Sassuolo signed Troianiello for €575,000 and 50% registration rights of Sansone for €425,000. In the 2012/13 season, Troianiello scored five goals and managed six assists in 31 appearances as his side were promoted from Serie B.
Palermo On 2 July 2013, he was signed by
Palermo for free. He was used only sparingly, making 16 appearances in all competitions as Palermo were promoted from Serie B.
Bologna Troianiello was loaned out from Palermo to Bologna for the 2014–15 season. He made only 11 appearances as Bologna achieved promotion from Serie B, making it his third successive promotion from Serie B, with three different clubs.
Salernitana Troianiello played the first half of the 2015–2016 season with Salernitana.
Ternana In January 2016, he was loaned out to
Ternana. He made 3 appearances in Serie B.
Verona On 31 August 2016, he was signed by
Verona.
Fano After being released by
Sambenedettese, he joined
Fano in February. ==Honours==