Auld was shelled a week earlier by the Thrashers, allowing five goals on eight shots in a 6-3 loss on Sept. 20. He was acquired in the offseason in the five-player trade that sent former All-Star goalie Roberto Luongo to Vancouver.
Auld made his best save in the first period when he stopped former Panthers captain Scott Mellanby from close in.
Martin Gelinas and Jay Bouwmeester scored second-period goals for Florida, which entered the game as one of only two winless teams in the preseason along with Carolina.
Atlanta dropped to 2-3.
Florida killed a 5-on-3 power play for 1:42 in the third period after being called for three penalties in a span of 1:10.
Kari Lehtonen stopped 34 of 36 shots for Atlanta.
Gelinas broke a scoreless tie at 13:28 of the second period when he tipped in Ruslan Salei's slap shot from the point on a power play.
Bouwmeester scored at 16:39 following a spectacular move by Nathan Horton.
Florida dominated play from the outset, outshooting Atlanta 17-9 in the first period and 36-26 overall.