Gallardo, who entered the game with a frightful 16.88 ERA and is scheduled to start Baltimore's second game of the regular season, needed just 48 pitches to complete five innings. He struck out two.
''Of course, anytime you go out there and pitch well, it's always a positive thing,'' Gallardo said. ''Especially the last one, it's very important to get that timing, get that rhythm down in the last start of spring training to prepare for the regular season. You've got to be ready. From here on out, there's no excuses.''
Jonathan Schoop hit a three-run home run off Atlanta starter Bud Norris, who pitched for the Orioles from 2013-15.
Norris, who is set to be the Braves' second starter, gave up three runs on six hits in five innings. He struck out six and walked none.
Xavier Avery hit a home run in a three-run eighth inning for Baltimore.
Braves: RHP John Gant, who followed Norris, pitched three innings and allowed three runs. According to manager Fredi Gonzalez, Gant has a good shot at winning the long relief role.
RHP Carlos Torres, who was scheduled to pitch, has exercised an opt-out in his minor league contract.
Orioles: Manager Buck Showalter named RHP Mike Wright as the team's fourth starter.
''Mike won the job,'' Showalter said. ''Mike pitched well this spring, and had a great year last year in Triple-A. It's his time. I don't know how much simpler you can make it.''
Showalter hasn't decided on his fifth starter, who could be RHP Tyler Wilson while Kevin Gausman begins the season on the disabled list. Wilson was told Thursday that he had made the team.
Baltimore is no closer to a resolution on the Hyun Soo Kim issue. Showalter met with Kim for the third time in an attempt to get the South Korean OF to agree to a demotion to Triple-A Norfolk.
Kim, who signed a two-year, $7 million contract in December, must consent to a minor league assignment.
OF Drew Stubbs, who was signed to a minor league contract, arrived in Florida early Thursday morning, Gonzalez said.
Gonzalez says he's going to give Stubbs at-bats over the final three games of spring training. Stubbs walked and flied out in his two at-bats.
''We're going to give him an opportunity,'' Gonzalez said. ''He can run. He can defend. He's got some pop. He's had a couple of good years offensively. He fits. We'll watch him for three days.''
Orioles: Gausman (shoulder), Brian Matusz (back) and Jimmy Paredes (wrist) are expected to start the season on the disabled list.
Braves: RHP Jhoulys Chacin starts against LHP Adam Wilk as they host the Tampa Bay Rays on Friday.
Orioles: RHP Vance Worley starts for the Orioles as they play at Philadelphia on Friday night. RHP Aaron Nola is scheduled for the Phillies.