The winger enjoyed 5 seasons as a regular for the 'Toffees', but fell out of favour last season after the arrivals of Yannick Bolasie and Theo Walcott to the club.
He spent the second half of last season at his former club Olimpiacos, scoring twice in 13 games.
On his return to Everton this summer he was given a chance in pre-season by Marco Silva, however it seemed that his exit was inevitable after Richarlison arrived from Watford in a £40 million deal.
He is on his way to Florence to complete a medical with the Italian outfit, who will have the option to make the move permanent at the end of the season for a reported £7 million, according to the 'Daily Mail'.
Mirallas's new club will hope that he will be able to help them improve their league performance from last season, as they missed out on a place in Europe by finishing 8th in Serie A.