The England international has been linked with Hull City and Monaco during the January transfer window, but the Toffees have won the race to take him from White Hart Lane.
The 27-year-old has fallen down the pecking order under Mauricio Pochettino, having started just three Premier League matches this season.
He will now look to help Roberto Martinez's side stave off relegation following a disappointing first half of the season.
"We all know what Aaron will bring to our squad with his experience and know-how, his involvement with England in two World Cups and the landmarks he has set in the Premier League," Martinez told the club's official website.
“At 27, Aaron will be a really important asset to our squad and he will represent a real boost in terms of attacking options from now to the end of the season. His pace and trickery will fit in well at Goodison.
