White says his "blood is boiling" to return to football. He'll compete with Chris Greisen, who led the Florida Tuskers to last season's UFL title game.
Terms of the deal weren't disclosed Monday.
White went 34-8 as a starter and led West Virginia to wins in the Sugar and Fiesta bowls.
He played in 13 games his rookie season with the Dolphins in 2009, going 0-of-5 passing and rushing for 81 yards on 21 carries.
White signed a minor league baseball contract with the Kansas City Royals after being released by the Dolphins last September. But White did not report to spring training and retired from baseball.