Brian McCann’s first-inning homer off Brian Matusz (5-7) gave Atlanta a 1-0 lead. The Orioles scored two runs off Tommy Hanson in the fourth with help from a throwing error by Simmons at shortstop and a fielding error by Michael Bourn in center field.
Chad Durbin (3-0) struck out the two batters he faced after taking over for Hanson in the sixth.
Simmons had three hits for the Braves, who snapped a four-game losing streak.
Matusz fell to 0-6 in seven career interleague starts. He gave up four runs, nine hits and three walks in 5 2-3 innings.
The Orioles began the night one-half game behind the first-place Yankees in the AL East. New York beat Washington 7-2.
Craig Kimbrel pitched the ninth for his 19th save.
The Orioles hit into four double plays to boost their total to 72, the most in the major leagues. Matt Wieters’ grounder to Simmons with the bases loaded in the third started an inning-ending double play. Pinch-hitter Nick Johnson hit into a double play to end the game.
Hanson showed his frequent disagreement with home plate umpire Derryl Cousins’ strike zone as he set a career-high with six walks in 5 1-3 innings.
Hanson gave up four hits and two unearned runs. He was pulled after consecutive walks in the sixth. He took a look at Cousins as he walked off the field.
The Braves made several strong defensive plays in the game, but the defense let Hanson down with two errors in the fourth.
Simmons’ homer drove in Matt Diaz to give Atlanta a 3-2 lead. It was the second homer for Simmons.