"There is still a great deal that I want this team to accomplish and I look forward to helping lead us to success in 2018," Grier said in a statement. "I am completely focused and looking forward to building off the success we had this year and want to do even greater things next year."
Grier, who began his college career at Florida, has thrown for 3,490 yards and 34 touchdowns this season and was named the Big 12 Newcomer of the Year. His touchdown total ranked seventh in the FBS for the regular season.
"Will's decision to return next year certainly makes it a great day for West Virginia football," coach Dana Holgorsen said in a statement. "He is a great leader for our program, and I know our fans enjoy watching his talents on the football field. His teammates and the coaching staff are certainly looking forward to his return, and this is positive news for all involved."
Grier missed West Virginia's regular-season finale with a broken finger; Chris Chugunov started in his place. The Mountaineers have not announced whether Grier will play against the Utes, but Holgorsen has said it's "going to be kind of tough" for him to return.