The Belgian spent half of last season out on loan at Greek side Olympiakos after failing to convince Ronald Koeman and Sam Allardyce of his value to the squad.
Mirallas joined Everton from Olympiakos in 2012 for a fee of £6m and has gone on to make 186 appearances for the club, scoring 39 goals.
However, with new manager Marco Silva looking to trim his squad, there appears to be no space for Mirallas at Goodison Park this season, leading to yet another loan move.
This time it appears it will be in a somewhat more reputable league, with the aforementioned source confident that a loan switch to Florence will be tied up within 24 hours.