Allan has joined United Arab Emirates club Al Wahda on a permanent transfer for an undisclosed fee.
The paperwork for the Brazilian midfielder was finalised on Tuesday.
Allan moves to the Abu Dhabi-based side, with the UAE transfer window open until 4 October.
The 31-year-old joined Everton in September 2020 from Serie A side Napoli, going on to make 57 appearances for the Blues.
Allan, who has 10 caps for Brazil, began his career in his homeland with Vasco da Gama before moving to Italy in 2012 for three seasons with Udinese.
Everton thanks Allan for his service and wishes him all the best for the future.