Previous reports suggested that the Spanish side would prefer a loan agreement with a purchase option , but the move is now understood to be a permanent one valued at £10.5 million.
And after holding Chelsea to a 0-0 draw on Wednesday, Wenger confirmed the 26-year-old is on his way out of Arsenal.
Asked by Sky Sports after the match if Coquelin was about to leave Arsenal, Wenger replied: "Yes."
Wenger later added at a post-match news conference: "He goes to Valencia, he didn’t get enough games.
"I let him go."
And he leaves the Emirates with an unwanted record to his name, his 160 games under Wenger without a goal the most of any outfielder during the Frenchman's 21-year reign.
Wenger was later asked if he planned to enter the transfer market to replace Coquelin, but the Frenchman stated that he would sooner have the likes of Aaron Ramsey and Mesut Ozil back from injury.
"The best way to replace him is getting [Aaron] Ramsey and [Mesut] Ozil back," he added.
"Then we’ll see. We have players injured."
Arsenal also have another injury worry in the midfield, with Jack Wilshere having been forced out of Wednesday's contest .