The 22-year-old struggled to cement a first-team place under David Moyes and spent the past two seasons on loan in Portugal
The 22-year-old, who moved to Goodison Park in June 2010 from Portuguese club Aves, has signed a three-year contract with Levski Sofia, according to reports in Bulgaria.
After signing for Everton, the Portugal Under-21 international was loaned out to Uniao Leiria for the enitre 2010-11 season. Upon returning, the Silva was then sent for a second loan spell in his homeland at Vitoria Setabal.
Everton boss David Moyes, who has already bolstered his attacking options with the signing of Steven Naismith from Rangers, has taken his squad to Austria to begin their pre-season preparations.