Trickett, who has two seasons of eligibility remaining, will start classes May 20 and can compete for the starting position immediately because of his status as a graduate student.
Trickett, 6-foot-3, 185 pounds, left Florida State after it became apparent redshirt freshman Jameis Winston had an edge in the competition at the end of spring practices.
Trickett completed 66 of 106 passes (62.3 percent) for 947 yards and seven touchdowns with four interceptions in two seasons of backup action.
He will compete with junior Paul Millard and freshman Ford Childress for the starting position. Millard has experience and Childress has a strong arm, but neither quarterback emerged in the spring, with both struggling to get the ball out as quickly as West Virginia would like.
Trickett lived in West Virginia for seven years while his father, Rick, was an offensive line coach there.
Clint Trickett has indicated that he likes the Mountaineers' style of offense and considers it an ideal fit and thinks he can release the ball quickly and stretch the field.
Trickett has the ability to make plays on the run and has played in several key games for Florida State, including relieving EJ Manuel against Oklahoma and starting against Clemson the following week.
Trickett chose West Virginia over Auburn and South Florida.