Everton have signed Watford midfielder Abdoulaye Doucoure on a three-year contract for a transfer fee understood to be £20m.
Doucoure, 27, has played in 129 Premier League games since joining the Hornets in January 2016, scoring 17 goals.
"I had some interest from other clubs but Everton was the only club I wanted to join," said Doucoure.
Watford rejected a £30m offer from Everton for the former Rennes midfielder last summer, but the Hornets have agreed to sell after being relegated from the Premier League.
"I have been waiting a long time to come here and now it has happened so I am very happy," said the ex-France Under-21 international.
"Everton has a big history in English football and is a good club for me to have a step up in my career. It is an ambitious project here and it was a big part of my decision."
With Niels Nkounkou also recruited, Doucoure is the Toffees' fourth summer signing.
They begin their top-flight campaign at Tottenham on Sunday, 13 September (16:30 BST).
Analysis - Ancelotti has rebuilt Everton's engine room in four days
Phil McNulty, chief football writer
Everton's ambition and the pulling power of manager Carlo Ancelotti have been graphically illustrated by a bold triple raid on the transfer market that has the Italian's touch stamped all over it.
Ancelotti, correctly, identified midfield as Everton's most serious flaw before taking his first steps to reshape the side in his own image.
And in the space of four days he has rebuilt the Everton engine room while at the same time bringing in players of high quality in Brazil's tough midfielder Allan, the stardust of James Rodriguez and the energy and quality of Abdoulaye Doucoure from Watford.
Everton owner Farhad Moshiri has never been shy of backing his managers but here his willingness has been supported by the presence of a man who can be regarded as managerial royalty.
Ancelotti earmarked Allan after they worked together at Napoli while Rodriguez, who worked with him at Real Madrid and on loan with Bayern Munich, was lured to Merseyside by the prospect of reuniting with the figure he considers a mentor.
The bottom line, however, is that neither Allan nor Rodriguez would have given a moment's consideration to the side that finished 12th in the Premier League if Ancelotti had not been at the club.
Doucoure has been a long-time Everton target and Watford's relegation finally got the deal over the line.
It has been an impressive show of strength in the market by Everton, with more to come, and has been exactly what Moshiri had in mind when he pulled off the coup of Ancelotti's appointment last December.
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