Harris is widely considered the top transfer in the nation.
Harris, a 6-foot-3 shooting guard, averaged 17.2 points per game for the Mountaineers last season as a sophomore.
Harris will have two years of college eligibility remaining, but will be forced to sit out the 2014-15 season due to NCAA transfer rules.
Michigan State coach Tom Izzo has three commitments for this season. Aside from Harris, the Spartans also have guard/forward Kyle Ahrens and power forward Deyonta Davis.