The option to buy was included in the loan deal for Wolves captain Coady.
The 29-year-old, who captained Wolves four times, has agreed to join the Goodison Park club.
With regular first-team football at Goodison Park, Coady has the chance to strengthen his claim to be included in the England squad for the World Cup.
It was the first time in over a year that Coady had been left out of a Wolves game shirt, and he was an unused substitute at Elland Road.
Coady, who has been capped 10 times by England, said it was incredible to join the club. I wanted to be a part of it immediately after hearing the interest from the manager and the football club. I'm very excited about joining.
I know a lot about the football club and what it means to the fans. I wanted to come here to play for this club. My family and friends are huge fans of the team.
I'm here to do my best for this football club. I need to help my team-mates, help the club move forward and make people proud.
He fits into how we want to play as a team and we're delighted to have him.
His leadership skills will be of huge benefit to us, as well as being one of the premier league's most reliable defenders.
Valencia have confirmed that they have reached an agreement with Wolves for the sale of their international player.
He scored 40 goals and registered 32 assists in 199 appearances for the Spanish club before moving to Wolves.
The club wished him the best of luck in his new career and thanked him for his professionalism.
The arrival of Coady brings much-needed reinforcements to Goodison Park after the club confirmed defender Ben Godfrey was facing a three-month lay-off after breaking his fibula.
The statement said that Ben had successful surgery this morning on his fractured fibula.
The defender is expected to be out for three months as he begins rehabilitation at the club's farm.
The seriousness of Yerry Mina's ankle injury is not yet known, but an update on his fitness was provided by the club.
"Yerry Mina sustained an ankle injury in the second half of Saturday's match and will see a specialist this week to discover the full extent of the problem before he undergoes treatment at Finch Farm."
The transfer window will close at 11pm on September 1st.
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