The move was announced at 9:30 pm, despite the seven pm deadline having passed, after paperwork, contractual details and the medical were finalised following a delay.
Those close to the deal had indicated on Sunday evening that the transfer was expected to go through, but Everton were forced to wait for formal approval before making it official.
George joins the Toffees on loan from Chelsea and took the Number 19 shirt ahead of the second half of the season. The young forward said he was eager to make an impact and embraced the challenge of playing for a club with Everton's history.
"I'm really excited to be here and to enjoy this massive club," George said. "I just can't wait to get started."
He also highlighted the importance of the supporters and the club's expectations. "The fans here are exceptional. I know Evertonians are really passionate. They like hard work - and that's what I'm going to show. I want to be exciting and I want to impress them."
George admitted manager David Moyes played a key role in his decision. "The gaffer was another reason I wanted to join," he said. "He's an amazing manager who has coached so many players, like Wayne Rooney. I've spoken to him briefly and he's an amazing person. I just want to learn under him and improve."
Everton hope George's energy and creativity will strengthen their attacking options for the rest of the season.
Tottenham Hotspur have confirmed the signing of teenage striker James Wilson on loan from Heart of Midlothian until the end of the season, with an option to make the move permanent in the summer.
Arsenal manager Mikel Arteta has said his side still had "a lot to do" despite holding a 3-2 lead ahead of Tuesday's League Cup semi-final second leg against an in-form Chelsea at the Emirates Stadium.
Liam Rosenior believes Arsenal are the "favourites" to reach Wembley as they prepare to host Chelsea in the second leg of their Carabao Cup semi-final on Tuesday night.
Tottenham face uncertainty in defence as Thomas Frank confirmed injuries to Kevin Danso, Micky van de Ven and Djed Spence after the 2-2 draw with Manchester City on Sunday.
