|Full name||Guillermo Gonzalo Giacomazzi Suárez|
|Date of birth||November 21, 1977|
|Place of birth||Montevideo, Uruguay|
|Height||1.87 m (6 ft 1 1⁄2 in)|
|2007||→ Palermo (loan)||7||(0)|
|2007–2008||→ Empoli (loan)||20||(0)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 1 August 2015|
He started in Uruguay, playing for Bella Vista before moving to Peñarol. In 2001, he was signed by U.S. Lecce and made his debut match in Italian Serie A on August 27, 2001, against Parma, a game which Lecce drew 1-1. He played for the team for the following 6 years, becoming its captain.
On January 31, 2007, he was signed by U.S. Città di Palermo. On February 11, 2007, he played his first Serie A match for Palermo, against Empoli F.C. In the following season he was loaned to Empoli, and in 2008 he returned to the Lecce squad. On 6 July 2010, he signed a new 4-year contract with Lecce.
Giacomazzi stayed with Lecce in 2012 despite their relegation from Serie A in 2011-12 and subsequent expulsion from the Serie B for their part in the Calcio Scommesse scandal. Giacomazzi, the club's captain, rejected offers from Serie A sides Parma and Torino and Serie B team Cesena to remain at the club.
In 2013, he joined Siena, a team that at the end of the season was excluded from the Serie B due to financial problems. Thus he became a free agent and joined A.C. Perugia for the 2014–15 Serie B season.
- "Ficha de Jugador de selección: Guillermo Giacomazzi". Tenfield. Archived from the original on April 23, 2009. Retrieved 2009-01-10.
- "SERIE A: GIACOMAZZI IL PIÙ PRESENTE IN A, "HO DATO TANTO E HO RICEVUTO TANTO"" (in Italian). Soccerpuglia.it. 2009-05-12. Archived from the original on 2011-07-22.
- "Tactical Formation". Football-Lineups.com. Retrieved February 15, 2007.
- "Rinnovo del contratto per Giacomazzi". US Lecce (in Italian). 6 July 2010. Retrieved 8 July 2010.
- "Lecce, Giacomazzi: "Ho respinto le offerte di Parma, Torino e Cesena"". TuttoMercatoWeb.
- "Giacomazzi è un giocatore del Perugia". ACPerugiaCalcio.com. Archived from the original on 2014-08-14.