Montella was sacked after the 4-1 loss to Roma, with a seven-match winless run in Serie A leading to Fiorentina making a change ahead of the mid-season break.

Iachini knows the club well, having played for the Viola between 1989 and 1994.

His last job in a coaching career that has included spells at Sassuolo, Sampdoria and Udinese, was at Empoli, though he was sacked after just four months in charge.

"I would like to thank Vincenzo Montella for the commitment and professionalism he showed during his time at the club," club president Rocco Commisso said in a statement.

"Unfortunately, our current league position forced us to make a change.

"We chose Iachini because he is a great person and has strong ties with Florence and Fiorentina. Now we all need to work together to get back on track as quickly as possible."

Iachini will have to wait for his first game in charge, however, as Fiorentina do not play again until January 6, when they travel to Bologna.