Lehtonen's effort came in his first appearance in more than seven weeks. He had been sidelined since Oct. 30 because of an ongoing back injury.
White's 10th goal this season at 18:23 of the first period was the eventual game-winner.
Tampa Bay got two goals from Martin St. Louis and one from Adam Hall.
Mike Smith was beaten four times on 30 shots for the Lightning, who have lost 17 of their last 19 games overall, and have not won at Atlanta since Feb. 22, 2007, when they won 5-4 in overtime.
On the power play, Tampa went 2-for-6 and Atlanta went 1-for-4.