The experienced midfielder is believed to be close to joining the Artemio Franchi side, after it emerged he was on the brink of terminating his contract at his current club
New Roma coach Zdenek Zeman no longer needs the veteran midfielder, and left him out of his squad for the club's pre-season tour to Austria.
The 32-year-old is under contract with Roma, but both parties have supposedly reached an agreement to terminate his deal with immediate effect.
His agent is now due to meet Giallorossi sporting director Franco Baldini later on Thursday to iron out the details of the player's contract.
Pizarro had previously been linked with Argentine side River Plate, but a prolonged stay in Serie A now seems to be on the cards, with the player set to undergo a medical in the next 24 hours before his switch to Fiorentina is finalised.
The Chilean midfielder spent the second half of the 2011-12 campaign on loan at Manchester City, and won the Premier League title with the Citizens.