On Saturday evening, the Superleague Greece champions confirmed via Twitter that a deal had been agreed with the Blues and the move was now subject to a medical and an agreement on personal terms.
The clubs are believed to have agreed on a loan fee in the region of £4 million, a cut-price fee that will finally see the Belgian winger depart Goodison Park - albeit temporary. The Greek club reportedly have no option to make the move a permanent one at the end of the season.
Mirallas, who joined Everton in 2012, found the back of the net 38 times in 186 appearances during a five-and-a-half-year spell with the Blues.
Over the past few seasons, the 30-year-old forward has become a fringe member of the Everton squad, struggling to find game time with all of the previous Blues bosses - Roberto Martinez, Ronald Koeman, David Unsworth and now Sam Allardyce.
A move to join up his first Everton boss David Moyes at West Ham United had been in the offing during this transfer window but Mirallas has reportedly had his heart set on a return to Olympiacos for some time.
The Hammers have attempted to make moves for Mirallas over the past few summers but have been unable to agree on a fee.
A loan move had been rumoured to be a possibility for the Belgian but current Blues boss Allardyce stated during the week that Everton would be unwilling to allow players to depart on loan during this window.
However, it looks as if the 63-year old boss has had a change of stance, allowing the Belgian to depart on loan.
The 30-year-old has been set for a Goodison Park exit for some time, with Allardyce finally being the Everton manager to sanction the departure.
Mirallas has become increasingly stale in his play - seemingly losing the mercurial spark that made him a success during the early part of his Everton career.
A rumoured training ground fallout with interim boss Unsworth and Duncan Ferguson seemingly signalled the end for a player who has, for plenty of Evertonians, been living on borrowed time for a number of seasons.