[3] He spent the vast majority of his career in Spain after starting out at Estudiantes, appearing in 313 La Liga matches over 14 seasons and scoring a total of 48 goals for Almería, Valencia, Espanyol and Elche.

[6][7] Initially an undisputed starter, notably netting in a 1–1 home draw against Real Madrid,[8] he struggled after the arrival, midway through his first season, of Mexican coach Hugo Sánchez.

In the 2009–10 campaign, without the presence of striker Álvaro Negredo, Piatti was much more depended upon in scoring matters and netted seven times in 35 matches, joint-second in the team as they finished in 13th position.

[14] Piatti scored his first official goal for Valencia on 19 January 2012, netting the 3–1 in the 45th minute of an eventual 4–1 home victory over Levante UD in the quarter-finals of the Copa del Rey.

[16] After Jordi Alba and Jérémy Mathieu developed an efficient left-wing partnership, Piatti was used inconsistently by managers Mauricio Pellegrino, Ernesto Valverde and Miroslav Đukić, also struggling with some injury problems.

[14] After the dismissal of Đukić due to poor results, however, new boss Juan Antonio Pizzi showed faith in his compatriot Piatti, who repaid the former's confidence by finishing 2013–14 with five league goals from 17 appearances, one of those coming in a 3–2 win at FC Barcelona.

[23] In February 2019, during a home match against Rayo Vallecano, Piatti suffered an injury to both his right knee's anterior cruciate and internal lateral ligaments, going on to be sidelined for several months.

[37][38] On 5 June 2011, Piatti made his debut for the senior side, as national team boss Sergio Batista handed him a start in a 2–1 friendly loss with Poland.