Born in Rio Claro, São Paulo, Cittadini started his career at Guarani, and was promoted to first team in 2010, under the management of Vágner Mancini.

After the arrival of Dorival Júnior he returned to action, being converted to a defensive midfielder in the 2016 season; he also rejected a loan move to Chievo in the process.

[14] On 10 April 2016 Cittadini scored his first goal after his return, netting his team's first in a 2–1 Campeonato Paulista home win against Audax.

On 6 November, after nearly two months without playing a single minute, he came off the bench to provide two assists in Santos' 2–1 away win against former club Ponte Preta; he ended up crying after the match was over.

Despite Vecchio left the club, he lost the starting spot to Diego Pituca and new signing Carlos Sánchez, being completely ostracized by new manager Cuca after refusing a contract renewal.