 On 26 August 2009, ACF Fiorentina signed the right-back from S.S. Lazio on a five-year deal, he was presented to the press in Florence on 27 August; on successive declarations, De Silvestri stated he had reluctantly decided to leave his favourite club due to his strained relationship with president Claudio Lotito.After an injury that prevented him from appearing in the early weeks of the season, De Silvestri became a regular under head coach Cesare Prandelli and completed the 2009–10 campaign with a total 27 appearances.Under new Fiorentina boss Siniša Mihajlović, De Silvestri was originally confirmed as a regular, but successively lost his place as a starter in favour of Gianluca Comotto after the poor performance the team.