White said 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.
"I didn't know whether or not this would happen," White told the Destroyers' official website. "It's a blessing, and playing (for the Destroyers) is a great opportunity."
Terms of White's deal weren't disclosed.
White went 34-8 as a starter and led West Virginia University to wins in the Sugar and Fiesta bowls.
"(White) is competitive, a good athlete, and a leader on the field and in the locker room," Destroyers director of player personnel Bret Munsey told the team's site. "We look forward to see what he can bring to the team."
White played in 13 games during 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 didn't report to spring training and retired from baseball.
The Associated Press contributed to this report.