The victory gave Cincinnati a six-game winning streak.
Votto's homer, his 21st, gave Cincinnati a 2-0 lead with one out in the top of the sixth.
Scott Rolen capped a three-run inning with an RBI single, only the fourth hit for the Reds, who have won 12 of their last 14 games.
Wells (1-3) walked four batters, struck out four, and the only hit he surrendered was a lead-off single by Garret Anderson in the bottom of the second.
Closer Francisco Cordero earned his 32nd save despite a walk and a hit in the bottom of the ninth.
Atlanta's run scored on Nate McLouth's seventh-inning single.
Two others had one hit for the Braves, who have lost four in a row.
The losing pitcher was starter Jair Jurrjens (10-10).
Copyright 2009 by United Press International.