Rookie Vaughn Grissom also went deep for the surging Braves, who won their fifth straight after losing four of five to the NL East-leading New York Mets.
''They can turn the page from the rough weekend,'' Braves manager Brian Snitker said. ''These guys are playing for today.''
Acuna was removed after his fourth at-bat in the seventh as a precaution to rest his surgically repaired right knee. The All-Star outfielder, who played in the first game, tore his ACL on the same field last July. The injury forced him to miss the remainder of the regular season and Atlanta's World Series championship run.
''I feel I've been playing with soreness for about a week now,'' Acuna said through a translator. ''It comes and goes and I'm playing through it. At this moment, I feel good.''
In the first game, Chadwick Thompson doubled twice, singled and drove in three runs to lead Atlanta to a 5-2 win.
Acuna's shot over the wall in center was his 26th career leadoff homer. He also has 10 career blasts on the first pitch, four against Miami.
Braves starter Ian Anderson, who was optioned to Triple-A Gwinnett Aug. 7 only to return temporarily as the 27th man for the doubleheader, scattered two runs in six innings. Anderson (10-6) gave up five hits, walked one and struck out four.
Although he reached double-digit victories in a season for the first time in his career, Anderson has struggled with command, prompting the demotion to the minors.
''Kudos to all of the guys in this locker room, I feel I've had a ton of run support these last few games,'' Anderson said of the double-digit milestone. ''That always helps, but it's definitely an accomplishment.''
The Marlins have lost 12 of 13 at home and scored 23 runs total through their first 12 games in August. They also have been held to three runs or less in their last 14 games, the longest stretch in the major leagues since the Chicago Cubs had a similar drought for 15 games in Sept. 1979.
Grissom made it 3-0 with a two-run shot in the fifth. The 21-year-old Grissom hit Marlins reliever A.J. Ladwig's first pitch over the wall in left-center for his second homer since being promoted from Double-A Mississippi on Monday.
Miami narrowed the deficit on Joey Wendle's RBI single in the fifth, but the Braves responded with Olson's solo blast in the sixth. Olson has homered in the first three games of the series.
''I'm not going up there and squaring it up every single time,'' Olson said. ''There are still some pretty poor at-bats mixed in. Nothing out of the ordinary, trying to be a little bit more grounded,''
Jesus Aguilar's leadoff homer in the bottom half got the Marlins within 4-2 before Olson hit a two-run single in the seventh.
The Marlins loaded the bases with two outs in the ninth after Kirby Yates walked JJ Bleday and Jacob StalIings. Raisel Iglesias relieved and got the second out before walking Peyton Burdick. Pinch-hitter Garrett Cooper lined out to center for Iglesias' 17th save and first with the Braves.
Tommy Nance pitched the first three innings of the planned bullpen game for Miami. Reinstated from the injured list before the second game, Nance (0-1) allowed one run, two hits, walked one and struck out six.
Olson homered, while Acuna and Robbie Grossman each had two hits in the first game.
Atlanta starter Kyle Muller scattered two runs and three hits in five innings. Recalled from Gwinnett earlier Saturday, Muller (1-1) walked one and struck out five. Immediately after Muller's outing, the Braves returned the left-hander to Gwinnett.
Chadwick Tromp's two-run double with the bases loaded capped a three-run fourth and put Atlanta ahead 3-0. Tromp experienced cramping in his left quad as he reached second, prompting immediate attention from Braves training personnel, but he remained in the game.
Miami reduced the gap on Aguilar's two-run homer in the bottom half.
The Braves recalled RHP Bryce Elder from Gwinnett for the second game.
The Marlins optioned RHP Jeff Brigham to Triple-A Jacksonville to open Nance's spot on the roster. Brigham threw two scoreless innings in the first game.
RARE HOME DOUBLEHEADER
The Marlins played their first nine-inning doubleheader at loanDepot Park since they moved to the retractable roof stadium in 2012. During the pandemic shortened 2020 season, the Marlins had three home doubleheaders, but those were reduced to seven-inning games.
Marlins: RHP Anthony Bender got the first two outs in the ninth in the second game before exiting with forearm discomfort. ... INF Jazz Chisholm Jr. (right lower back strain) continues to rehab at the club's spring training facility in Jupiter, but has not moved into baseball activities. ... OF Avisail Garcia (left hamstring strain) is continuing his strengthening exercises and began a running program Friday.
RHP Bryce Elder (1-3, 5.48) will start the series finale for the Braves Sunday and the Marlins will go with LHP Braxton Garrett (2-6, 4.02).
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