Bolasie joined the Toffees in a £30m move from Crystal Palace in 2016 but has struggled for both form and fitness since arriving at Goodison Park.
The 29-year-old missed almost a year of football shortly after signing for the club after suffering cruciate knee ligament damage against Manchester United.
The former Crystal Palace winger is yet to feature this season and has fallen down the pecking order at Everton following the arrival of Brazilian duo Richarlison and Bernard.
Bolasie was pictured by Sky Sports in the stands at Villa Park on Wednesday, watching the 2-2 draw with Brentford, and the DR Congo international says he is determined to help Villa secure promotion back to the top-flight.
“My main aim here is to get this club promoted,” he said. “A club of this stature has to be in the Premier League.
“I looked around both Villa Park and the training ground, and me and my family just said, ‘wow’. It’s Premier League everywhere you look.
“I’m here to make myself smile again and use all my ability to try and help the team. It’s great to be here.”
Villa also completed the signing of winger Anwar El Ghazi from Lille on a season-long loan deal on Wednesday.