Olsen (2-0) struck out three and did not walk a batter. He threw 84 pitches, 62 for strikes.
Josh Willingham hit an RBI triple, stole two bases and scored once for the Marlins. Mike Jacobs added a pair of doubles for his fifth consecutive multi-hit game.
Atlanta starter Jair Jurrjens (1-2) gave up two runs and four hits in six innings.
Olsen, who entered 1-4 with an 8.54 ERA against the Braves, left with a 2-0 lead. Renyel Pinto and Kevin Gregg each pitched an inning to complete the six- hitter, Florida's first shutout since a 4-0 victory over the St. Louis Cardinals on July 17.
Willingham, who went 2-for-3, came in with 10 stolen bases in 326 career games.
Willingham scored the first run in the fourth when he walked with two outs, stole second and came home on Jacobs' first double.
That snapped a streak of 10 consecutive Florida runs coming off homers.
The Marlins increased their lead to 2-0 in the sixth when Willingham tripled home Dan Uggla, who led off with a double. Florida scored twice in the eighth inning when Braves reliever Will Ohman walked pinch hitter and former Atlanta Brave Wes Helms and former Augusta GreenJacket Hanley Ramirez with the bases loaded.
The Braves' only threat against Olsen came in the sixth when Kelly Johnson and Yunel Escobar opened the inning with singles. But Olsen got Chipper Jones and Mark Teixeira to fly out before Jeff Francoeur grounded out to end the inning.
Jones, who came in leading the National League with a .408 batting average, singled in his first two at-bats and ended up 2-for-4.
Jurrjens was effective but for the second consecutive game had little run support. In his six innings, he struck out five and walked three, but also pitched his way out of trouble.
After Willingham's triple, he intentionally walked Jacobs to set up the double play. He then struck out Jorge Cantu swinging but Jacobs stole second on the play.
Catcher Mike Rabelo then flied out to center fielder Mark Kotsay to end the inning. In both of Jurrjens' losses this season, the Braves have only scored three runs.
In his lone victory, Atlanta scored 10 off of Pittsburgh in their third game of the year.
The Braves left six runners on base and failed to score with runners in scoring position with two outs.
Florida scored three of its four runs with two outs.