Digne, 28 ends his four-year stay at Goodison Park to join Steven Gerrard's side on a permanent deal.
Gerrard said: "When Lucas became available we jumped at the opportunity to bring him to the club.
"To sign a player of his pedigree and quality in the January window is a great addition to our squad and his arrival excites me and everyone associated with Aston Villa."
"It was the main factor. I came here for the manager," Digne said."I had a very good meeting with him and we spoke a couple of times during this month.
I feel his desire to win, to show his football as a manager -- the attacking football, the possession. I feel it's what I want and what I want to show to the fans."
Chelsea were originally interested in signing Digne after Ben Chilwell was ruled out for the rest of the season following knee surgery.
ESPN reported on Dec. 31 that Chelsea were keen on a loan move but the situation was complicated by Everton's preference for a straight transfer and other clubs indicating they would be willing to meet the £25 million asking price.
Although sources have told ESPN that Digne was keen on a move to Stamford Bridge, Chelsea boss Thomas Tuchel was not keen on making a permanent signing given Chilwell is expected to make a full recovery.
"He has been very clear," Benitez said at a recent news conference. "I want to ask a question to every fan and former players -- what Peter Reid would do if a player comes out and says he doesn't want to be there?
"That's it -- simple. I've had a couple of conversations with him and he told me what he thought so what do you expect the manager to do when a player is thinking of leaving?"
Digne joined Everton from Barca in August 2018 and made over 120 appearances for the Merseyside club, scoring 20 goals in the process.
Both Digne and Coutinho could make their debuts when Villa host Manchester United in the Premier League on Saturday.
Meanwhile, in a separate deal, Everton signed Villa's Anwar El Ghazi on loan until the end of the season.
"I'm really excited. Everton is a big club, I cannot wait to get started," El Ghazi told evertontv on Thursday.
"I can always score a goal in an important moment. I can add a lot of value with my pace and technique going forward. I can hold the ball and I am decent in one-on-ones. I am ready and can't wait.
"If I can score goals like the one I scored against Everton, for Everton now, then I will be a happy man."
Information from ESPN's James Olley was included in this report.